JavaScript (ES2026) reference · JSON and Global Functions

JavaScript parseInt() Function

Parse an integer from the start of a string in a given base. Always pass the radix, e.g. parseInt("08", 10).

JavaScript (ES2026) Since ES1

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Syntax

parseInt(string, radix)

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

An integer or NaN.

Parse integersTry it yourself

console.log(parseInt("42", 10), parseInt("42.9", 10), parseInt("  7 apples", 10));

Output

42 42 7

Hex prefixes and empty inputTry it yourself

console.log(parseInt("0x1A"), parseInt("1A", 16), parseInt(" ", 10));

Output

26 26 NaN

Version	Change
JavaScript ES1	Added

Number.parseInt() · Parse an integer from the start of a string in a given base (radix). Always pass the radix, usually 10.
parseFloat() · Parse a decimal number from the start of a string, stopping at the first character that can't be part of it.
JavaScript Type Conversion · tutorial