JavaScript (ES2026) reference · Number Methods and Properties

JavaScript Number.parseInt() Method

Parse an integer from the start of a string in a given base (radix). Always pass the radix, usually 10.

JavaScript (ES2026) Since ES2015

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Syntax

Number.parseInt(string, radix)

Parameter	Description
`string`	The text to parse.
`radix` optional	Base from 2 to 36.

An integer or NaN.

Different basesTry it yourself

console.log(Number.parseInt("42px", 10), Number.parseInt("ff", 16), Number.parseInt("101", 2));

Output

42 255 5

Truncates decimals; NaN when nothing parsesTry it yourself

console.log(Number.parseInt("3.99", 10), Number.parseInt("abc", 10));

Output

3 NaN

Version	Change
JavaScript ES2015	Added

Number.parseFloat() · Parse a decimal number from the start of a string, ignoring trailing text. Same as the global parseFloat().
number.toString() · Convert a number to a string, optionally in another base such as 2 (binary) or 16 (hexadecimal).
parseInt() · Parse an integer from the start of a string in a given base. Always pass the radix, e.g. parseInt("08", 10).
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