The role of parseint function

The parseint function is to parse an integer from a string and return the parsed integer value. Detailed introduction: In the parseInt function, when a string is passed in, it will try to parse the integer from the beginning of the string. Once a non-numeric character is encountered, parsing stops and the parsed integer part is returned. This means that non-numeric characters in the string are ignored.

The parseInt function is a built-in function in JavaScript that is used to convert strings to integers. Its function is to parse an integer from a string and return the parsed integer value.

Here is an example of using the parseInt function:

let num1 = parseInt("10"); // 返回整数值 10
let num2 = parseInt("20.5"); // 返回整数值 20
let num3 = parseInt("30px"); // 返回整数值 30

In the parseInt function, when a string is passed in, it will try to parse the integer starting from the beginning of the string. Once a non-numeric character is encountered, it stops parsing and returns the parsed integer part. This means that non-numeric characters in the string are ignored.

In addition, the parseInt function can also accept a second parameter, which is used to specify the base used for parsing. For example:

let num4 = parseInt("10", 2); // 以二进制解析，返回整数值 2
let num5 = parseInt("10", 8); // 以八进制解析，返回整数值 8
let num6 = parseInt("10", 16); // 以十六进制解析，返回整数值 16

It should be noted that in ECMAScript 5, if the incoming string starts with "0x" or "0X", the parseInt function will parse it into hexadecimal. in ECMAScript 3, for strings starting with 0, the parseInt function will parse them into octal, which may lead to some unexpected results. So in ECMAScript It is recommended in 5 to always use the second parameter to explicitly specify the parsing base.

In short, the function of parseInt function is to parse a string into an integer, and you can specify the base used for parsing.

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