How to convert string to number in es6

Conversion method: 1. Use parseInt() to convert the string to an integer, the syntax "parseInt("string")"; 2. Use parseFloat() to convert the string to a floating point number, the syntax "parseFloat ("string")"; 3. Use the multiplication operator, the syntax is "numeric string * 1".

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

Method 1: Use parseInt() to convert to an integer

console.log(parseInt("12345red"));	//返回 12345
console.log(parseInt("0xA"));	//返回 10
console.log(parseInt("56.9"));	//返回 56
console.log(parseInt("red"));	//返回 NaN
console.log(parseInt("AF", 16));	//返回 175
console.log(parseInt("10", 2));	//返回 2
console.log(parseInt("10", 8));	//返回 8
console.log(parseInt("10", 10));	//返回 10

//如果十进制数包含前导 0，那么最好采用基数 10，这样才不会意外地得到八进制的值
console.log(parseInt("010"));	//返回 8
console.log(parseInt("010", 8));	//返回 8
console.log(parseInt("010", 10));	//返回 10

Output result:

Method 2: Use parseFloat() to convert to floating point number

console.log(parseFloat("12345red"));	//返回 12345
console.log(parseFloat("0xA"));	//返回 NaN
console.log(parseFloat("11.2"));	//返回 11.2
console.log(parseFloat("11.22.33"));	//返回 11.22
console.log(parseFloat("0102"));	//返回 102
console.log(parseFloat("red"));	//返回 NaN

Output result:

Method 3 : Use the multiplication operator

If a variable is multiplied by 1, the variable will be automatically converted to a numeric value by JavaScript. After multiplying by 1, the result is unchanged, but the type of the value is converted to a numeric value. If the value cannot be reduced to a legal number, NaN is returned.

var a = 1;  //数值
var b = "1";  //数字字符串
console.log(a + (b * 1));  //返回数值 2

[Recommended learning: javascript advanced tutorial]

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