• The original address: Everything about the latest ECMAScript release | ECMAScript 2021
  • Kritika Sharma
  • The Nuggets translation Project
  • Permanent link to this article: github.com/xitu/gold-m…
  • Translator: Hoarfroster
  • Proofread by: KimYang, tong-h

In this article, we’ll walk you through the latest version of ECMAScript 2021 with some sample code.

The new function

1. String.replaceAll( )

Replace all instances of the target string found with the desired string:

const fact = "JavaScript is the best web scripting language. JavaScript can be used for both front end and backend";
 
console.log(fact.replaceAll("JavaScript"."TypeScript"));

/ / output:
// "TypeScript is the best web scripting language. TypeScript can be used for both front end and backend";
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Compare this to the previous replace() method, which replaces only the first match of the target string with the desired string:

const fact = "JavaScript is the best web scripting language. JavaScript can be used for both front end and backend";
 
console.log(fact.replace("JavaScript"."TypeScript"));

/ / output:
// "TypeScript is the best web scripting language. JavaScript can be used for both front end and backend";
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2. Promise.any( )

As soon as any of the supplied promises are resolved, promise.any () is resolved directly, while promise.all () is marked as resolved until all promises are resolved, basically the opposite of promise.all ().

If “Keeping a Promise” :

const promises = [   
          Promise.reject('A' wrong),           
          Promise.reject(Error 'B'),   
          Promise.resolve('results')];Promise
  .any(promises)
  .then((result) = > assert.equal(result, 'results')); //true
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If “All promises are rejected” :

const promises = [   
          Promise.reject('A' wrong),  
          Promise.reject(Error 'B'),   
          Promise.reject('error C')];Promise
  .any(promises)   
  .catch((aggregateError) = > {
            assert.deepEqual(aggregateError.errors, 
            ['A' wrong.Error 'B'.'error C']); //true
   });
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3. Logical assignment operators

A | | = b is equivalent to a | | (a = b) (short-circuit operator)

Why not a = a | | b?

Well, because for the previous expression, the assignment is only performed if A evaluates to false. Therefore, the former is assigned only when necessary. In contrast, the latter expression always performs assignment.

An example of a | | = b:

var a = 1;  
var b = 2;  
 
a ||= b;   

console.log(a); / / 1
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An example of a &&= b:

var a = 1; 
var b = 2; 

a &&= b; 

console.log(a); / / 2
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a ?? An example of = b:

var a;  
var b = 2; a ?? = b;console.log(a); / / 2
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4. Numeric delimiters

We can now use an underscore (_) as a separator between numeric and bigInt text. This will help developers improve the readability of their numeric text (the “underscore” will basically act as the “comma” we use to write numbers in everyday life (to provide separation between groups of numbers).

let budget = 1000000000000; // You can write:

let budget = 1 _000_000_000_000; 

console.log(budget); // Print normal numbers:

/ / output:
/ / 1000000000000
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Hopefully, this article has helped you keep up with the latest version of ECMAScript. Thank you for reading and feel free to comment if you have any questions.

References:

  • Dev. To/faithfuloje…
  • 2 ality.com/2020/09/ecm…

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