How to determine whether it is a number in es6

In es6, you can use the isFinite() method of the Number object to determine whether the value is a number. This method can detect whether the passed parameter value is a finite number; the syntax is "Number.isFinite(value)".

The operating environment of this tutorial: Windows 7 system, ECMAScript version 6, Dell G3 computer.

ES6 provides us with a method to determine numbers. For details, see the code below.

Number.isFinite determines numbers.

The Number.isFinite() method is used to detect whether the incoming parameter is a finite number.

let a = 1
console.log(Number.isFinite(a)); // true
console.log(Number.isFinite("beline")); //false
console.log(Number.isFinite(NaN)); // false  
console.log(Number.isFinite(undefined)); // false

Number.isNaN determines non-number

console.log(Number.isNaN(NaN)); // true
console.log(Number.isNaN(1)); // false

Number.isInteger determines whether it is an integer

let a = 66
console.log(Number.isInteger(a)); // true

If you need to determine whether it is a floating point type, just add the negation sign in front of the object

let a = 111.77
console.log(!Number.isInteger(a)); // The safe value range of true

safe integers

in computer numerical types is 2 to the 53rd power.

let num = Math.pow(2, 53) - 1;
console.log(num) // 9007199254740991

Why does ES6 provide constants for the maximum safe integer and the minimum safe integer? You can also use the isSafeInteger method to determine whether the incoming value is within the safe integer range. In daily work, if this number is exceeded, We need to convert this value into a string and display it to the user

console.log(Number.MAX_SAFE_INTEGER) // 9007199254740991
console.log(Number.MIN_SAFE_INTEGER) // -9007199254740991
// Determine whether num is within the safe integer range console.log(Number.isSafeInteger(num)) // true