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JavaScript Number parseInt() Method
Last Updated : 6 Feb, 2026
The parseInt() method parses a value by converting it to a string and returns the first integer found. It also accepts an optional radix parameter that specifies the base of the numeral system.
- Converts a string into an integer value.
- Supports different number systems using the radix parameter.
- Stops parsing when a non-numeric character is encountered.
JavaScript
// Basic string to integer conversion
console.log(parseInt("123"));
// Stops at non-numeric character
console.log(parseInt("45px"));
// Using radix parameter (base 2)
console.log(parseInt("1010", 2));
// Invalid conversion
console.log(parseInt("abc"));
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]: Using Parsing float value
javascript
let v1 = parseInt("3.14");
console.log('Using parseInt("3.14") = '+ v1);
[Example 2]: Parsing value with given radix
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);
