Add ES2019 Object.fromEntries function

Search Terms

fromEntries

Suggestion

lib: es2019 should add Object.fromEntries() type.

Use Cases

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/fromEntries

Examples

Checklist

My suggestion meets these guidelines:

This wouldn't be a breaking change in existing TypeScript/JavaScript code
This wouldn't change the runtime behavior of existing JavaScript code
This could be implemented without emitting different JS based on the types of the expressions
This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
This feature would agree with the rest of TypeScript's Design Goals.

https://github.com/tc39/proposal-object-from-entries

HI Guys,

Is this live yet and if so, which version? I can't get it to find it as Property 'fromEntries' does not exist on type 'ObjectConstructor'.

What versions of TS and NODEJS should I be running to make this work?

The file is available in my node_modules under lib.es2019.object.d.ts but it won't read from it?

Any link to any issue regarding how to resolve a similar issue is welcomed.

/// <reference no-default-lib="true"/>


/// <reference lib="es2015.iterable" />

interface ObjectConstructor {
    /**
     * Returns an object created by key-value entries for properties and methods
     * @param entries An iterable object that contains key-value entries for properties and methods.
     */
    fromEntries<T = any>(entries: Iterable<readonly [PropertyKey, T]>): { [k in PropertyKey]: T };

    /**
     * Returns an object created by key-value entries for properties and methods
     * @param entries An iterable object that contains key-value entries for properties and methods.
     */
    fromEntries(entries: Iterable<readonly any[]>): any;
}

HI Guys,

Is this live yet and if so, which version? I can't get it to find it as Property 'fromEntries' does not exist on type 'ObjectConstructor'.

What versions of TS and NODEJS should I be running to make this work?

It looks to me that in tsconfig.json, the setting to use is target: "es2019" or greater. This means it won't work in all browsers and typescrcipt does no magic to use this.

this is what I did

declare global {
  interface ObjectConstructor {
    fromEntries(xs: [string|number|symbol, any][]): object
  }
}

const fromEntries = (xs: [string|number|symbol, any][]) =>
  Object.fromEntries ? Object.fromEntries(xs) : xs.reduce((acc, [key, value]) => ({...acc, [key]: value}), {})

Benny Powers (@bennypowers)

Extending Benny Powers (@bennypowers) to sort an object similar to this:

{
  foo: 'bar',
  baz: 'boo',
  alpha: 'beta',
}

use

Object.keys(input).sort().reduce((acc, cur) => ({ ...acc, [cur]: input[cur] }), {})

I ended up just defining my own functions for what I needed. They're pretty gross since they use any, but they get the job done for me I think:

function fromEntries<T>(entries: [keyof T, T[keyof T]][]): T {
  return entries.reduce(
    (acc, [key, value]) => ({ ...acc, [key]: value }),
    <T>{}
  );
}

function toEntries<T>(obj: T): [keyof T, T[keyof T]][] {
  const entries: [string, any][] = Object.entries(obj);
  const entriesWithKeysLookedUp: [keyof T, T[keyof T]][] = entries.map(item => {
    const keyString = item[0];
    const value = item[1];
    return [<keyof T>keyString, value];
  });
  return entriesWithKeysLookedUp;
}

All I wanted to do was map an objects values. Ended up being way more annoying than it should have been. Does anyone know a better way? It's annoying that Object.entries returns [string, T] and not a keyof type since you know the first element in each of the array elements is a keyof something and not just a string.

Casey Howard (@caseyhoward)

Casey Howard (@caseyhoward) , Hi. I have a problem with the {} construct. TypeScript 3.8.3. http://www.typescriptlang.org/v2/en/play?useDefineForClassFields=true&allowUnreachableCode=true&allowUnusedLabels=true&downlevelIteration=true&target=99

Cannot use JSX unless the '--jsx' flag is provided.(17004)
'T' only refers to a type, but is being used as a value here.(2693)
JSX element 'T' has no corresponding closing tag.(17008)

Do you know the solution?

Go into tsconfig.json, and inside compilerOptions properties search for a property named lib. Add the string "esnext" in the array. It should look something like:

"lib": ["es2018", "dom", "esnext"]

Add ["esnext"] to the lib worked for me! Thank u

Hi All,
I am seeing this issue with chrome version 70 line , Angular TS
tsconfig : "lib": [ "es2018", "dom", "esnext" ]
one thing to notice the vendor js in lazy loaded as the .

with the uses of Object.fromEntries in .ts throws the same error in chrome 70 line .

case .ts : main.ts:12 TypeError: Object.fromEntries is not a function at new AppComponent (app.component.ts:15) at NodeInjectorFactory.AppComponent_Factory [as factory] (app.component.ts:18) at getNodeInjectable (core.js:5993) at instantiateRootComponent (core.js:12873)

case Vendor : VM547 vendor.js:98199 Uncaught TypeError: Object.fromEntries is not a function at Module.<anonymous> (VM547 vendor.js:98199) at i (VM547 vendor.js:98199) at push../node_modules/@ckeditor/ckeditor5-build-decoupled-document/build/ckeditor.js (VM547 vendor.js:98199) at VM547 vendor.js:98199 at VM547 vendor.js:98199 at Object../node_modules/@ckeditor/ckeditor5-build-decoupled-document/build/ckeditor.js (VM547 vendor.js:98199) at __webpack_require__ (VM542 runtime.js:85) at __webpack_require__ (VM542 runtime.js:85) at Module../src/app/shared/shared.module.ts (VM545 main.js:2147)

what is the right match so that all the dependency can be added in compile ?

but adding this to the polyfills make it work for all the cases .
import "core-js/es/object/from-entries";

ame right ?

*platform is web .

intention is to support the newer libs for older codebase dependency .

Thanks ,
Apurba M.

go to "tsconfig.json" and adding :

"lib": ["es2019"];

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Add ES2019 Object.fromEntries function #30933

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Add ES2019 Object.fromEntries function #30933

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Suggestion

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Examples

Checklist

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iugo commented on Apr 24, 2019

waynevanson commented on Aug 9, 2019

waynevanson commented on Aug 11, 2019

waynevanson commented on Aug 11, 2019

bennypowers commented on Feb 16, 2020

tsujp commented on Feb 17, 2020

caseyhoward commented on Feb 26, 2020

MrCheater commented on Mar 4, 2020

javiermrz commented on Aug 7, 2020

dmorenogogoleva commented on Jan 26, 2021

mapurba commented on Apr 1, 2021

sadeghmasoomi commented on Apr 26, 2022

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