New Javascript features in ES12-2021

1. replaceAll

• syntax "<string>".replaceAll(<pattern>);

• Phương thức này trả về một chuỗi string mới đã được thay thế theo pattern.

• Example:

   const p = 'The quick brown fox jumps over the lazy dog. If the dog reacted, was it really lazy?'; console.log(p.replaceAll('dog', 'monkey')); // Output: "The quick brown fox jumps over the lazy monkey. If the monkey reacted, was it really lazy?"
  

• <pattern> là một string hoặc cũng có thể là một regex

   const p = 'The quick brown fox jumps over the lazy dog. If the dog reacted, was it really lazy?'; const regex = /Dog/ig; console.log(p.replaceAll(regex, 'ferret')); // expected output: "The quick brown fox jumps over the lazy ferret. If the ferret reacted, was it really lazy?"
  

2. Promise.any

• Promise any nhận vào 1 mảng Promise Object, và nó sẽ reslove sau khi có 1 Promise Object trong mảng resolve
• Example:

   const promise1 = Promise.reject(0); const promise2 = new Promise((resolve) => setTimeout(resolve, 100, 'quick')); const promise3 = new Promise((resolve) => setTimeout(resolve, 500, 'slow')); const promises = [promise1, promise2, promise3]; Promise.any(promises).then((value) => console.log(value)); // Output: "quick"
  

3. Logical Assignment Operator

• Logical Assignment Operator sẽ combine(cho phép kết hợp) giữa toán tử logic và biểu thức gán.
• Example:

   a ||= b // equals to a = a || (a = b) a &&= b // equals to a = a && (a = b) a ??= b // equals to a = a ?? (a = b)
  

4. Underscores as Numeric Separator

• Example:

   const billion = 1_000_000_000; console.log(billion); // 1000000000 1_000_000_000 === 1000000000; // true
  

Refer Javascript-es2021-you-need-to-see-these-es12-features