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