Typescript is obscurely particular with accessing attribute keys on objects that lack a generic signature. The values can be scalar values or functions or even array of other objects. This time, due to a mistake, one of the books has been assigned with the price 0.. Let’s find the book with the price 0 and log its name to console. Asking for help, clarification, or responding to other answers. How to create and type JavaScript variables. Of course, this is very unsafe. This might look like strange behavior but Typescript is doing the right thing. Summary: in this tutorial, you will learn about the TypeScript static properties and methods.. Static properties. "someproperty does not exist on type", but on the type it does exist, Add to your question the code which defines the type of. Even if the property name exists (but has undefined value), hero.name !== undefined evaluates to false: which incorrectly indicates a missing property.. 4. However, the property/method distinction is little more than a convention. Is it safe to keep uranium ore in my house? Getting value out of maps that are treated like collections is always something I have to remind myself how to do properly. your coworkers to find and share information. Does this actually work? How would a theoretically perfect language work? {{name}} Type definition for object literal in Typescript Example. Stack Overflow for Teams is a private, secure spot for you and See the additional edit above that preserves the object previous type. type safety throughout because you don't need to use the, uses TypeScript's aggregate type (as denoted by the. To access a static property, you use the className.propertyName syntax. And we can access the properties of class object just like we access the elements of JSON object, using dot operator. ', or even ' ' (a space). identifier is the name of the property to access and expression should evaluate to an object. Unfortunately, you cannot access nested arrays with this trick Summary. Soul-Scar Mage and Nin, the Pain Artist with lifelink, My friend says that the story of my novel sounds too similar to Harry Potter. Extending @jmvtrinidad solution for Angular. This way, the next level key will always be accessed from an object that exists or an empty object, but never from undefined.. Advanced Types. The type of each property name will have to be one of the keys of the previous property. Join Stack Overflow to learn, share knowledge, and build your career. In this post I look at JavaScript object iteration and picking out values from a JavaScript object by property name or index. To learn more, see our tips on writing great answers. How can I hit studs and avoid cables when installing a TV mount? It is possible to denote obj as any, but that defeats the whole purpose of using typescript. As shown above, an object can contain scalar values, functions and structures like arrays and tuples. at the end of the property name in … Sometimes the TypeScript compiler isn’t able to determine what type of value it may at a certain point. Suppose we created an interface 'I' with properties x and y. Asking for help, clarification, or responding to other answers. If you want an object to basically have any property, then you can explicitly mark a value any and the TypeScript compiler won’t infer the type from the assigned object … var obj: IType = {}; obj['code1'] = { prop1: 'prop 1 value', prop2: 'prop 2 value' }; TypeScript in 5 minutes. This is a type-safety check in JavaScript, and TypeScript benefits from that. However, this will work. In both cases, this is contingent on the value matching a publicly accessible property name of the given object’s type. With the keyof keyword we can cast a given value to an Index type or set a variable to the property name an object. Sort array of objects by string property value, Can't bind to 'ngModel' since it isn't a known property of 'input', I found stock certificates for Disney and Sony that were given to me in 2011. Is it safe to keep uranium ore in my house? How to provide types to functions in JavaScript. Podcast 305: What does it mean to be a “senior” software engineer, How to solve TypeScript error: Property does not exist on type '{}'.ts(2339). However, there are some cases where TypeScript at the time of this writing needs a little bit more assistance from us. I tend to put any on the other side i.e. widening the type (read: extend/specialize the interface), cast the original object to the extended type. How do I prevent the error “Index signature of object type implicitly has an 'any' type” when compiling typescript with noImplicitAny flag enabled? The ordering of the enumerable properties in the array is consistent with the ordering exposed by a for...in loop (or by Object.keys()) over the properties of the object. Can Pluto be seen with the naked eye from Neptune when Pluto and Neptune are closest? I think this is the best solution now. Object.entries(hero) returns the entries of hero: [['name', 'Batman'], ['city', 'Gotham']]. car.owner = "ibrahim"; // You can set a property: use any type. Here's a Typescript-friendly way to verify an attribute exists in an object, and then access that attribute. TypeScript: using dynamic properties Although I really like static typing and the other great features that TypeScript brings to JavaScript, sometimes I just want to profit from the dynamic nature of JavaScript. This is just a convention in TypeScript, available for convenience. For example: If you want to access some arbitrary property that is not defined in the type signature of the object, you can use the ["foo"] notation, and the type checker will not try to enforce that the instance you're accessing has such a property in its type signature. The real elegance of this solution is that you can include typesafe fields in the interface. Within the lib.es6.d.ts … Object.assign works the best when you have flatter objects. Making statements based on opinion; back them up with references or personal experience. The parsed JSON string is loaded to an object of specified TypeScript class. While you can use the super keyword to access a public method from a derived class, you can’t access a property in the base class using super (though you can override the property). How to make sure that a conference is not a scam when you are invited as a speaker? In TypeScript, the interfaces which describe objects can have optional properties. Typescript error: TS7053 Element implicitly has an 'any' type, Typescript access dynamic property with [' '] syntax, Dynamic object key with Typescript in React event handler. No compiler errors and works like a charm. That includes the toString() and the hasOwnProperty() methods, for example. How does one defend against supply chain attacks? They let us declare a constructor parameter and a member in one place. document ['createElement'] ('pre') Let’s assume you have a JavaScript object where you don’t know if a certain property exists. Better to not use Object or {}, but some named type; or you might be using an API with specific types, which you need extend with your own fields. const variable = object [property_name] object [property_name] = value; This does the exact same thing as the previous example. Otherwise, it's still just a string. If so, what exactly does it say? We could add this to get or set, depending what you want to do.Above, I’m using set so that each time our property is accessed, we don’t have to keep adding the prefix each time get is called (which is every time the property is accessed).. In the above code, we define a property salary and set enumerable property as false.This will make the salary hidden from the Object.keys. How do I dynamically assign properties to an object in TypeScript? This doesn't mean you cannot get the name of a class in JS. #The Object Type. Do you get an error? There are different ways to define dynamic properties. What exactly does "doesn't work" mean? Would coating a space ship in liquid nitrogen mask its thermal signature? How is the seniority of Senators decided when most factors are tied? In JavaScript, this doesn't work: typeof obj return "object" or something else, but never the name of the class. TypeScript lets you augment an interface by simply declaring an interface with an identical name and new members. This is just a convention in TypeScript, available for convenience. Working for client of a company, does it count as being employed by that client? There are mainly 3 ways to check if the property exists. var foo:IFoo = {}; So something like this is still typesafe: Alternatively you can mark these properties as optional: This solution is useful when your object has Specific Type. How am I supposed to assign any new property to an object in TypeScript? I try with your code, but I don't receive any error: How do I dynamically assign properties to an object in TypeScript? obj = {} implies obj is an Object. Object.assign has it's own unique aspects (that are well known to most experienced JS devs) that should be considered when writing TypeScript. How to get the least number of flips to a plastic chips to get a certain figure? Element implicitly has an 'any' type because type 'Object' has no index signature. Output. With strict null checking enabled, TypeScript forces you to ensure that an object is defined before accessing its property. To declare a static property, you use the static keyword. Object.entries(hero) returns the entries of hero: [['name', 'Batman'], ['city', 'Gotham']]. You can create new object based on the old object using the spread operator. It can be used in a mutable fashion, or an immutable manner (I demonstrate the immutable way above, which means that. key-value pairs), use: It is possible to add a member to an existing object by. Here’s an example: const hero = { name: 'Batman' }; const { name } = hero;name; const { name } = hero is an object destructuring. nameof is just one of the tricks in the book that makes life a little easier when you want the type safety of knowing that the string you type is a property on a given object. car['owner'] = "ibrahim"; // You can add a property: var car:any = {type: "BMW", model: "i8", color: "white"}; There are mainly 3 ways to check if the property exists. The type of object is not safe inside getObject, which means object.a will be of type string even before its assignment. What should I do? It's typical when speaking of an object's properties to make a distinction between properties and methods. After compiling I still have {} in my javascript. The callback function could calculate other properties too, to handle the case where the color is the same, and order by a secondary property as well: The new dynamic property will only be available when you use the cast: If you are using Typescript, presumably you want to use the type safety; in which case naked Object and 'any' are counterindicated. Instead, we'll require that the key actually exists on the type of the object that is passed in: function prop < T, K extends keyof T >(obj: T, key: K) {return obj[key];} TypeScript now infers the prop function to have a return type of T[K], a so-called indexed access type or lookup type. in .NET, it's easy to get the class name of an object using obj.GetType().Name. I think at the time the question was asked index properties like this were not yet implemented in TypeScript. Summary. This got me most of the way there, so thank you. Adding generic signatures reduces type-safety though. It does make sense when you have dynamic data. If you must create an empty object first, then pick one of these two solutions. How do I cast a JSON Object to a TypeScript class? Deep property access in TypeScript. There are lots of possibilities for use cases, parsing date objects, checking lengths of arrays, if properties exist on an object you passed … I had a JavaScript/TypeScript object where I wanted to set a property value: In TypeScript, this generates an error: The property 'prop' does not exist on value of type '{}' To … Truesight and Darkvision, why does a monster have both? I am trying to understand why, when trying to access dynamic object property I can do the following as I saw on one of the answers here: I am trying to understand, why the first method works for accessing/assigning to dynamic objects. @AjaxLeung You should very rarely cast to. Object.getOwnPropertyNames() returns an array whose elements are strings corresponding to the enumerable and non-enumerable properties found directly in a given object obj. Getting value out of maps that are treated like collections is always something I have to remind myself how to do properly. Example: Object Literal Notation var person = { firstname:"Tom", lastname:"Hanks" }; //access the object values console.log(person.firstname) console.log(person.lastname) On compiling, it will generate the same code in JavaScript. One more option do to that is to access the property as a collection: I'm surprised that none of the answers reference Object.assign since that's the technique I use whenever I think about "composition" in JavaScript. to Earth, who gets killed. Keep in mind that every time you use as, you're losing safety. TutorialKart com Conclusion. For more information on Index types and the keyof keyword, check out the Typescript documentation. Summary: in this tutorial, you will learn about the TypeScript static properties and methods.. Static properties. Unlike an instance property, a static property is shared among all instances of a class. Now if you want to use otherProperty in html side, this is what you'd need: Angular compiler treats $any() as a cast to the any type just like in TypeScript when a or as any cast is used. TypeScript: How to handle this case without 'any' type declaration? My previous university email account got hacked and spam messages were sent to many people. When we return 1, the function communicates to sort() that the object b takes precedence in sorting over the object a.Returning -1 would do the opposite.. Thank you! In the above section you had learnt how to define property of type string and its initialization. Without strictNullChecks, it would be pretty straightforward. ES6's Object.assign function is used to copy the values of all of the enumerable own properties from one or more source objects to a target object. site design / logo © 2021 Stack Exchange Inc; user contributions licensed under cc by-sa. TypeScript infers the return type of this function to be T[K] and when we will call this function TypeScript will infer the actual type of the property that we're going to read: let user = { name : 'John Doe' , age : 25 } ; let name = getProperty ( user , 'name' ) ; // string let age = getProperty ( user , 'age' ) ; // number Unlike an instance property, a static property is shared among all instances of a class. If you watch out for the order of the Object.assign arguments, you should be fine. 2019-02-26 ⭐️ Check out my Advanced TypeScript book ⭐️ ... we need to define a signature that takes the object and N property names. In the object[property_name] syntax, the property_name is just a string or Symbol. In this post I look at JavaScript object iteration and picking out values from a JavaScript object by property name or index. While this answers the Original question, the answer here by @GreeneCreations might give another perspective on how to approach the problem. It represents the type of the property K of the type T. Checking if an array of dates are within a date range, Classic short story (1985 or earlier) about 1st alien ambassador (horse-like?) How is the seniority of Senators decided when most factors are tied? Similarly, there is way to define type for the property if the property is object literal. your coworkers to find and share information. We could fix it by using type assertion const value = dog[key as keyof Dog] but we already know that this is not ideal. Join Stack Overflow to learn, share knowledge, and build your career. All of this works because TypeScript allows us to index any object as long as the index's type is a union of all the possible keys, so it knows that the key is valid. 3.1 Entries in practice: find the property having 0 value. Like when obtaining the object to other source. dynamically assign properties to an object in TypeScript. To make these types of situations easier, a while back, TypeScript made it possible to use “dotted” property access syntax like person.name when a type had a string index signature. Any arbitrary object's instance 'o' can be declared with type 'I' if 'o' has same properties x and y; this feature is known as "Duck Typing". How to limit the disruption caused by students not writing required information on their exam until time is up. How do you explicitly set a new property on `window` in TypeScript? Question asked before here, answer by Angelo R is the one I am interested in. The first way is to invoke object.hasOwnProperty(propName).The method returns true if the propName exists inside object… In Typescript, an interface can be used to describe an Object's required properties along with their types. To access a static property, you use the className.propertyName syntax. @AjaxLeung If you need to do that, you are using it wrong. Store any new property on any kind of object by typecasting it to 'any': Later on you can retrieve it by casting your extended object back to 'any': Here is a special version of Object.assign, that automatically adjusts the variable type with every property change. Justifying housework / keeping one’s home clean and tidy, How to draw on a tikz picture without shifting it, 9 year old is breaking the rules, and not understanding consequences. How can I add a property to a class dynamically in typescript? Again, let’s use the books object that holds the prices of some books. Making statements based on opinion; back them up with references or personal experience. rev 2021.1.20.38359, Stack Overflow works best with JavaScript enabled, Where developers & technologists share private knowledge with coworkers, Programming & related technical career opportunities, Recruit tech talent & build your employer brand, Reach developers & technologists worldwide. The first way is to invoke object.hasOwnProperty(propName).The method returns true if the propName exists inside object… Functions. By adding the exclamation mark ( ! ) map, dictionary, hash, lookup table). nice, but in case you need to use prop2 in e.g. We are not referencing the property value by a narrow 'name' literal which type checker knows is an existing property of the Dog type but by using more general string type. The keys in this array are the names of the object's properties. Just make sure you instanciate all non-optional properties directly after it, to avoid bugs biting you later on. To get these values, you access them like this: For example: Again, let’s use the books object that holds the prices of some books. If you are receiving dynamic data from API, to build form, and then sending back dynamic values to api, it does make sense. With this notation, you’ll never run into Cannot read property ‘name’ of undefined.You basically check if user exists, if not, you create an empty object on the fly. How to develop a musical ear when you can't seem to get in the game? What do you call a 'usury' ('bad deal') agreement that doesn't involve a loan? JavaScript primitive types inside TypeScript. How many dimensions does a neural network have? Marking it as any makes no sense. // implicitly typed object const myObj = { Hello: "world" }; const myObjKey = " I resorted to dynamically composing the object and assigning it in one line, then assigning the dynamic properties in successive lines. In this example we use the constructor to declare a public property position and a protected property speed in the base class. After the destructuring, the variable identifier contains the property value. Interfaces with optional properties are written similar to other interfaces, with each optional property denoted by a ? TypeScript - Objects - An object is an instance which contains set of key value pairs. If you are combining two nested objects that contain nullable properties, you can end up overwriting truthy values with undefined. JSON syntax. I've learned something new today, thank you. Does it take one hour to board a bullet train in China, and if so, why? Variable Declarations. Layover/Transit in Japan Narita Airport during Covid-19, 9 year old is breaking the rules, and not understanding consequences. What's the point of TypeScript if I have to cast so many things to. prop3, will be hard to implement, Not sure if I follow the statement - there is no, This is if 'noImplicitAny: false' on the tsconfig.json, the best solution for me. It is a much cleaner alternative for key-value pairs where property-names are not known. LooseObject can accept fields with any string as key and any type as value. The object might be any or unknown. This answer worked for me because for facebook login I had to add properties to the. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. After 8 years this answer saved my day! The ordering of the non-enumerable properties in the array and the ordering among the enumerable properties is not defined. Type definition in object literal in TypeScript, The property 'value' does not exist on value of type 'HTMLElement'. To accomplish the desired consistency an interface could be defined as follows. How to provide a type shape to JavaScript objects. Any is there for a reason, obviously you should strongly type most of stuff which is not dynamic, but in dynamic cases you can't strongly type. Stack Overflow for Teams is a private, secure spot for you and Instead, we'll require that the key actually exists on the type of the object that is passed in: function prop < T, K extends keyof T >(obj: T, key: K) {return obj[key];} TypeScript now infers the prop function to have a return type of T[K], a so-called indexed access type or lookup type. Interfaces. Can anti-radiation missiles be used to target stealth fighter aircraft? The sum of two well-ordered subsets is well-ordered. Even if the property name exists (but has undefined value), hero.name !== undefined evaluates to false: which incorrectly indicates a missing property.. 4. TypeScript language extensions to JavaScript. What is the preferred syntax for defining enums in JavaScript? To declare a static property, you use the static keyword. to do that You just need to use typescript interfaces like so: interface IValue { prop1: string; prop2: string; } interface IType { [code: string]: IValue; } you can use it like that . The best practice is use safe typing, I recommend you: To preserve your previous type, temporary cast your object to any. This also made it easier to transition existing JavaScript code over to TypeScript. One of the best things in TypeScript, is automatic assignment of constructor parameters to the relevant property. TypeScript will infer all the fields of the original object and VSCode will do autocompletion, etc. Enforcing the type of the indexed members of a Typescript object? class Car { public … +1 for being the only solution that keeps type safety. More about this in the TypeScript specification: Typescript access dynamic property with [' '] syntax, Podcast 305: What does it mean to be a “senior” software engineer. To learn more, see our tips on writing great answers. yes well, this is not really type script way, you loose intellisense. The type of object is safe inside getObject, which means object.a will be of type string | undefined. These properties are called Parameter properties. TypeScript and JavaScript provide great flexibility on the client side to work with objects. This is the correct solution for one-off assignments. The TypeScript language doesn't include a nameof operator like in C#, but you can make one yourself easily: const nameof = (name: keyof T) => name; All this does is take a type and a string and return the string: interface Person { firstName: string; lastName: string; } const personName = nameof ("firstName"); //returns "firstName". Teams is a private, secure spot for you and your coworkers to find and information... ) methods, for example: TypeScript - objects - an object, is! Then pick one of the object type, and that 's the object and N property.... The warnings out of maps that are treated like collections is always something have! Provide a type shape to JavaScript objects before accessing its property my.... Alternative for key-value pairs ), cast the original object and VSCode will do autocompletion, etc you all. A constructor parameter and a member in one place describe objects can have optional properties are similar! This solution is that you can create new object based on opinion ; back them up references! New members can not get the name of an object in TypeScript you need to prop2... Using dot operator where property-names are not known that takes the object and N property names this solution that... Old is breaking the rules, and then access that attribute issue where LaTeX refuses to produce than.... we need to do properly knowledge, and that 's the object and assigning in! Aggregate type ( read: extend/specialize the interface is not really type script way, you use the syntax... Typescript at the time of this solution is that you can include typesafe fields the! More assistance from us be of type string and its initialization a signature that takes the object type and out..., use: it is possible to generate an exact 15kHz clock pulse an. Add a member in one place index properties like this were not yet implemented in?! To denote obj as any, but that defeats the whole purpose of using TypeScript when and. Safe to keep intellisense had to add a member in one place ; back them up with references personal! Thing as the previous example syntax, the answer here by @ GreeneCreations might give perspective. Let us declare a static property is shared among all instances of a TypeScript class original question, the which. To debug issue where LaTeX refuses to produce more than a convention Airport during Covid-19 9! Variable is not defined window ` in TypeScript, available for convenience to myself! 'S the point of TypeScript if I have to cast so many to. Javascript, and if so, why does wolframscript start an instance which contains set of key pairs! Which means that books object that holds the prices of some books you augment an interface with identical! In an object in TypeScript, the property_name is just a convention in TypeScript, is automatic assignment constructor. Real elegance of this writing needs a little bit more assistance from us relevant property feed, and... Properties in an object void, unlike Object.assign I tend to put any on the value matching a accessible! Some cases where TypeScript at the time typescript access object property by name this solution is that you can Function.name. Describe objects can have optional properties are written similar to other answers for me because for facebook I... Define a signature typescript access object property by name takes the object type, temporary cast your object to class... ’ s use the, uses TypeScript 's aggregate type ( read: extend/specialize the interface ), cast original. Objects dynamically for object with dynamic structure ( can not get the least number of flips to a plastic to... Does the exact same thing as the new object based on the other side i.e can include typesafe in. Value ; this does n't involve a loan to transition existing JavaScript code over to.... To do properly fashion, or responding to other answers, object ( lowercased ) represents all non-primitive,! Of Mathematica frontend properties in the game 7 pages a Typescript-friendly way to this... A static property, you should be fine best practice is use safe typing, recommend... Type declaration type ( as denoted by a by property name of a class our tips on writing great.. Senators decided when most factors are tied 'bad deal typescript access object property by name ) agreement that does n't work '' mean same! Resorted to dynamically composing the object and N property names give another perspective on to... ` in TypeScript, is automatic assignment of constructor parameters to typescript access object property by name extended type you require declaration to silence warnings... You ca n't seem to get the least number of flips to a class with expandable properties in an,. Temporary cast your object to a class ).Name the, uses 's... Of TypeScript if I have to remind myself how to develop a musical ear when you ca seem! Property/Method distinction is little more than 7 pages typescript access object property by name in JavaScript, and not understanding consequences with! Property from a JavaScript object where you don ’ t know if certain! Secure spot for you and your coworkers to find and share information facebook login I had to add new on! Keyof keyword, check out the TypeScript documentation a signature that takes the object 's properties an! Have < any > { } in my house back them up with or! Way there, so thank you to accomplish the desired consistency an interface with identical! An object in TypeScript by Angelo R is the name of the given object ’ s assume you have JavaScript! The right thing is object literal in TypeScript, the interfaces which describe objects can have optional properties written... Cc by-sa making statements based on opinion ; back them up with references personal. This writing needs a little bit more assistance from us ( read extend/specialize. The additional edit above that preserves the object and VSCode will do autocompletion, etc this were not yet in! Written similar to other answers available for convenience TypeScript class composing the object and VSCode will do autocompletion etc! All the fields of the previous example do autocompletion, etc this to work: assign! Flips to a TypeScript class is obscurely particular with accessing attribute keys objects. Typescript at the time of this solution is that you can create new object type, and TypeScript benefits that... To make sure you instanciate all non-optional properties directly after it, to avoid bugs biting you later.... Immutable way above, which means object.a will be undefined or null the keys in this example use. Common to all JavaScript objects documentation ) debug issue where LaTeX refuses to produce more 7... Being employed by that client space ship in liquid nitrogen mask its thermal signature space ) the parsed JSON is. String to number in TypeScript constructor to declare a static property is shared among all instances a... Constructor to declare a public property position and a protected property speed the! Opinion ; back them up with references or personal experience two nested objects lack! Compiler that there is way to verify an attribute exists in an application! And not understanding consequences call a 'usury ' ( 'bad deal ' ) agreement that n't... S see how pets_1 looks like as an associative array ( a.k.a the exact same thing as the object! Although the compiler complains it should still output it as you require the best is... Little more than 7 pages a string to number in TypeScript, is automatic assignment constructor. As being employed by that client time you use the static keyword I look at JavaScript where! And new members but that defeats the whole purpose of using TypeScript of constructor parameters to extended. By clicking “ post your answer ”, you use the books object that holds the of... To a TypeScript class any way to define a signature that takes the 's... Subscribe to this this but to keep uranium ore in my house and Darkvision,?., there are some cases where TypeScript at the time of this writing needs a little bit typescript access object property by name assistance us... Value pairs it wrong for more information on index types and the hasOwnProperty ( and... By simply declaring an interface ' I ' with properties x and y protected property speed in the section... Key value pairs Pluto and Neptune are closest accessing its property because for facebook login I had to add property. A loan index properties like this were not yet implemented in TypeScript a much alternative... Typescript at the time of this writing needs a little bit more assistance us. ' ) agreement that does n't mean you can not be defined in an interface ' I with. Typesafe fields in the above section you had learnt how to limit the disruption caused by students writing! A type shape to JavaScript objects TypeScript and JavaScript provide great flexibility on the other side i.e you learnt... Under cc by-sa losing safety the ordering among the enumerable properties is safe! On how to add a member in one line, then assigning the dynamic properties in array! Obj is an object in TypeScript, the answer here by @ GreeneCreations might give another on! Values, functions and structures like arrays typescript access object property by name tuples easy to get the name of an in... Refuses to produce more than a convention the indexed members of a class ) dynamically assign properties the! With the naked eye from Neptune when Pluto and Neptune are closest when working a! Is way to this RSS feed, copy and paste this URL into your reader! New property to access a static property, you should be fine - an object that you. However, there is way to this RSS feed, copy and paste this URL into your reader! And that 's the object and assigning it in one line, assigning. Let the TypeScript compiler that there is way to define type for the typescript access object property by name is object literal something new,! By the convert a string or Symbol function ( documentation ) let ’ s type to JavaScript objects?. The destructuring, the property_name is just a string to number in TypeScript specified TypeScript class string and its..