When employing TypeScript, an error pops up stating "cannot find name 'ObjectConstructor'" when attempting to use Object.assign

Question

When employing TypeScript, an error pops up stating "cannot find name 'ObjectConstructor'" when attempting to use Object.assign

I am rephrasing my query as I realized it was unclear earlier.

I have an API that is sending me data in the following format:

{"photos":[{"id":1,"title":"photo_1_title"}]}

In my code, I have a variable called photos and a function named getPhotos()

For implementing infinite scroll, I call getPhotos() once I reach the bottom of the page.

photos: any;

getPhotos() {
  this.photoService.getPhotos()
    .subscribe(
      photos => this.photos = photos
      // However, instead of replacing this.photos with new data, I want to merge the new array of photos using Object.assign, but I'm facing an error.
    )
}

When I make another call to get data and receive

{"photos":[{"id":2,"title":"photo_2_title"}]}

, I aim to update this.photos to look like:

{"photos":[{"id":1,"title":"photo_1_title"}, {"id":2,"title":"photo_2_title"}]}

Could someone assist me in understanding why
jsfiddle.net/ca46hLw9 isn't functioning properly? Isn't the assign method supposed to merge object contents together?

javascript typescript

Answer 1

Answer №1

Object.assign is a feature introduced in ECMAScript 2015 and is not available in ECMAScript 5 or earlier versions.

If you are compiling your TypeScript code for ECMAScript 5, the assign method may not be defined in the Object interface.

To resolve this issue, you have several options:

1. Change your TypeScript compiler configuration to target ECMAScript 2015 by setting target: 'es6'.

2. Extend the ObjectConstructor interface with the assign method like this:

declare interface ObjectConstructor {
    assign(...objects: Object[]): Object;
}

(Remember that redeclaring an interface extends it instead of overwriting it.)

3. Coerce the Object to any and ignore its typing:

(<any>Object).assign( this.photos, photos )

Keep in mind that if you intend to support older browsers, you will need to include a polyfill for ECMAScript 2015 features. Most modern browsers have decent support for ES2015, but there may still be compatibility issues.

TypeScript does not provide a polyfill for Object.assign when targeting ECMAScript 5 or earlier. Alternatively, Babel offers plugins for polyfills, so consider integrating Babel into your build process. Check out: https://babeljs.io/docs/plugins/transform-object-assign/

Finally, you can opt to use libraries like Lodash or jQuery, which have their own implementations of Object.assign, known as extend.

Answer 2

Object.assign is a feature introduced in ECMAScript 2015 and is not available in ECMAScript 5 or earlier versions.

If you are compiling your TypeScript code for ECMAScript 5, the assign method may not be defined in the Object interface.

To resolve this issue, you have several options:

1. Change your TypeScript compiler configuration to target ECMAScript 2015 by setting target: 'es6'.

2. Extend the ObjectConstructor interface with the assign method like this:

declare interface ObjectConstructor {
    assign(...objects: Object[]): Object;
}

(Remember that redeclaring an interface extends it instead of overwriting it.)

3. Coerce the Object to any and ignore its typing:

(<any>Object).assign( this.photos, photos )

Keep in mind that if you intend to support older browsers, you will need to include a polyfill for ECMAScript 2015 features. Most modern browsers have decent support for ES2015, but there may still be compatibility issues.

TypeScript does not provide a polyfill for Object.assign when targeting ECMAScript 5 or earlier. Alternatively, Babel offers plugins for polyfills, so consider integrating Babel into your build process. Check out: https://babeljs.io/docs/plugins/transform-object-assign/

Finally, you can opt to use libraries like Lodash or jQuery, which have their own implementations of Object.assign, known as extend.

Answer 3

Answer №2

Starting from Typescript version 2.1 and above, you have the option to utilize Object spread syntax.

let obj = { x: 1, y: "string" };
var newObj = {...obj, z: 3, y: 4}; // { x: number, y: number, z: number }

The sequence in which spread operations are specified determines the outcome of properties included in the final object; properties from subsequent spreads take precedence over those created earlier.

Answer 4

Starting from Typescript version 2.1 and above, you have the option to utilize Object spread syntax.

let obj = { x: 1, y: "string" };
var newObj = {...obj, z: 3, y: 4}; // { x: number, y: number, z: number }

The sequence in which spread operations are specified determines the outcome of properties included in the final object; properties from subsequent spreads take precedence over those created earlier.

Answer 5

Answer №3

To update to typescript version 2.0 or above, simply adjust the tsconfig.json file by adding "es6" to the "lib" section:

"lib": [
  "es5",
  "es6",
  "dom",
  "es2015.collection"
]

Answer 6

To update to typescript version 2.0 or above, simply adjust the tsconfig.json file by adding "es6" to the "lib" section:

"lib": [
  "es5",
  "es6",
  "dom",
  "es2015.collection"
]

When employing TypeScript, an error pops up stating "cannot find name 'ObjectConstructor'" when attempting to use Object.assign

Answer №1

Answer №2

Answer №3

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