JavaScript Number parseInt() Method

Last Updated : 11 Jul, 2025

TheparseInt method parses a value as a string and returns the first integer. It accepts a string argument and optional radix parameter, defining the numeral system base. This method is commonly used for converting string representations of numbers into integers.

Example:

The method takes two parameters: the string to be parsed and the radix (optional, default is 10).
2 = binary, 8 = octal, 10 = decimal, 16 = hexadecimal.

Syntax

parseInt(Value, radix);

Parameters

Value: This parameter contains a string that is converted to an integer.
radix: This parameter represents the radix or base to be used and it is optional.

Return value

It returns a number and if the first character can't be converted to a number then the function returns NaN. It returns a number parsed up to that point where it encounters a character that is not a number in the specified radix(base).

Example 1: Parsing float value

Here, we are using the parseInt() method to parse the given float value.

javascript

let v1 = parseInt("3.14"); console.log('Using parseInt("3.14") = '+ v1);

Output

Using parseInt("3.14") = 3

Example 2: Parsing value with given radix

Here, we will also mention radix with the number.

javascript

// Base 10 a = parseInt("100", 10); console.log('parseInt("100",10) = ' +  a); // Base 8 b = parseInt("8", 8); console.log('parseInt("8",8) = ' +  b); // Base 8 c = parseInt("15", 8); console.log('parseInt("15",8) = ' +  c); // Base 16 d = parseInt("16", 16); console.log('parseInt("16",16) = ' +  d); // Leading and trailing spaces are ignored // in parseInt() function e = parseInt(" 100 "); console.log('parseInt(" 100 ") = ' +  e); // Base 16(hexadecimal) f = parseInt("0x16"); console.log('parseInt("0x16") = ' +  f);

Output

parseInt("100",10) = 100 parseInt("8",8) = NaN parseInt("15",8) = 13 parseInt("16",16) = 22 parseInt(" 100 ") = 100 parseInt("0x16") = 22

We have a complete list of JavaScript Number constructor, properties, and methods list, to know more about the numbers please go through that article.