Typescript class instance to javascript object

Question

This is my code:

class A{ test: string constructor(test: string){ this.test = test } } const a = new A("hi") console.log(a) 

This is my output:

A { test: 'hi' }

When I want to upload this as a Javascript object, it get's rejected because it ain't a Javascript object. I can make one by doing this:

const someJSON = JSON.stringify(a) const javascriptObject = JSON.parse(someJSON) 

But I think there must be a better way, this feels like a hack. How to convert a typescript class instance to a plain javascript object?

Answer 1

If you want a plain JS object instead of a class instance you can spread the properties for example:

class A{ constructor(test){ this.test = test } } const a = new A("hi"); const b = { ...a }; console.log('a:', a); console.log('b:', b); console.log('Is b instance of A:', b instanceof A);

Answer 2

You can use Object.setPrototypeOf() to set the prototype of your symbol explicitly to the default prototype of objects, which is Object.prototype:

class A { constructor(test) { this.test = test } } const a = new A("hi") Object.setPrototypeOf(a, Object.prototype); console.log({ a, proto: Object.getPrototypeOf(a) });

This will make a equal to { test: "hi" }.

Answer 3

You may need to add methods to your class in future, some properties may become private. So add a method toObject. Then you will be able to use methods and provide data to api in needed format.

class A{ constructor(private _test: string){ } public toObject(){ //return JSON.parse(JSON.stringify(this)); //in case if you want to have underscored private let object = {}; Object.keys(this).map((key: string) => { object[key.slice(1)] = this[key]; }); return object; } } const a = new A("hi") console.log(a); console.log('----------------------'); console.log(a.toObject());