JavaScript parseInt() Function

❮ JavaScript Global Functions


Parse different strings:

var a = parseInt("10") + "<br>";
var b = parseInt("10.00") + "<br>";
var c = parseInt("10.33") + "<br>";
var d = parseInt("34 45 66") + "<br>";
var e = parseInt(" 60 ") + "<br>";
var f = parseInt("40 years") + "<br>";
var g = parseInt("He was 40") + "<br>";

var h = parseInt("10", 10)+ "<br>";
var i = parseInt("010")+ "<br>";
var j = parseInt("10", 8)+ "<br>";
var k = parseInt("0x10")+ "<br>";
var l = parseInt("10", 16)+ "<br>";

var n = a + b + c + d + e + f + g + "<br>" + h + i + j + k +l;

The result of n will be:

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Definition and Usage

The parseInt() function parses a string and returns an integer.

The radix parameter is used to specify which numeral system to be used, for example, a radix of 16 (hexadecimal) indicates that the number in the string should be parsed from a hexadecimal number to a decimal number.

If the radix parameter is omitted, JavaScript assumes the following:

  • If the string begins with "0x", the radix is 16 (hexadecimal)
  • If the string begins with "0", the radix is 8 (octal). This feature is deprecated
  • If the string begins with any other value, the radix is 10 (decimal)

Note: Only the first number in the string is returned!

Note: Leading and trailing spaces are allowed.

Note: If the first character cannot be converted to a number, parseInt() returns NaN.

Note: Older browsers will result parseInt("010") as 8, because older versions of ECMAScript, (older than ECMAScript 5, uses the octal radix (8) as default when the string begins with "0". As of ECMAScript 5, the default is the decimal radix (10).

Browser Support

parseInt() Yes Yes Yes Yes Yes


parseInt(string, radix)

Parameter Values

Parameter Description
string Required. The string to be parsed
radix Optional. A number (from 2 to 36) that represents the numeral system to be used

Technical Details

Return Value: A Number. If the first character cannot be converted to a number, NaN is returned
JavaScript Version: ECMAScript 1

❮ JavaScript Global Functions