Array.prototype.includes

Includes is a useful method on an Array to quickly find if an Array contains an element, including NaN (so unlike indexOf).

(() = > {
  let arr = [1.2.3.NaN];

  if (arr.includes(2)) {
    // Find if 2 exists in arR array
    console.log("Found it!); //>> Found!
  }
  if(! arr.includes(2.3)) {
    // The second parameter 3 represents the item with subscript 3 in the array, which is the fourth item to start the search
    console.warn("It doesn't exist!); //>> Does not exist!
  }

  The following two sentences explain the difference between incluedes and indexOf
  console.log(arr.includes(NaN)); //true
  console.log(arr.indexOf(NaN) != -1); //false}) ();Copy the code

Infix notation for exponential functions

This is a feature related to math.pow, remember i++,x += x, and infix notation for exponential functions is similar. Like the Python language, JavaScript uses the two-star ** symbol for Math.pow. The benefits are twofold:

  • A. Infix notation is more concise than functional notation, which makes it preferable.
  • B. Convenient calculation in mathematics, physics, robotics and other fields.
X ** y = x ** y

let squared = 2支那2;// Is equivalent to: 2 * 2
let cubed = 2支那3;// Is equivalent to: 2 * 2 * 2
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X **= y

let a = 2;
a **= 2;A = a * a;

let b = 3;
b **= 3;// a = b* b* b**; 支那
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That’s right, it’s a very sweet syntax candy.