How to determine whether a positive number or a negative number in JavaScript

JavaScript method to determine whether a positive number or a negative number: 1. Use the comparison operator ">" or "<" to determine whether a number is greater than 0 or less than 0, and then determine whether a positive number or a negative number; 2 , Use the sign() method of the Math object, the syntax is "Math.sign(value)".

The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.

Method 1: Use comparison operator “>” or “<”

var a=1;
if(a>0){
 console.log("正数");
}else if(a<0){
console.log("负数");
}else{
console.log("都不是");
}

正数

Method 2: Use Math.sign()

Math.sign(x);

x: It can be any number.

• Because sign is a static method of Math, you should use Math.sign() instead as a member of a Math object you create. method (Math is not a constructor).

• rather than as a method on the Math object you create (Math is not a constructor).

• This function has 5 return values, namely 1, -1, 0, -0, and NaN; each represents a positive number, a negative number, positive zero, negative zero, and NaN.

• The parameters passed into this function will be implicitly converted to numeric types.

const positive = 5;
const negative = -5;
const zero = 0;
Math.sign(positive); // 1
Math.sign(negative); // -1
Math.sign(zero); // 0

javascript advanced tutorial]

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