JavaScript (ES2026) reference · String Methods

JavaScript String padStart() Method

Pad the start of a string until it reaches a target length, for example zero-padding numbers like 007.

JavaScript (ES2026) Since ES2017

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Syntax

string.padStart(targetLength, padString)

Parameter	Description
`targetLength`	The length of the result.
`padString` optional	Text to pad with. Default: `" "`

A new string.

Zero-pad numbersTry it yourself

console.log(String(7).padStart(3, "0"), String(42).padStart(5));

Output

007    42

Mask all but the last fourTry it yourself

const card = "4242424242424242";
console.log(card.slice(-4).padStart(card.length, "*"));

Output

************4242

Version	Change
JavaScript ES2017	Added

string.padEnd() · Pad the end of a string with another string until it reaches a target length. Useful for aligned text columns.
string.slice() · Extract part of a string between two indexes; negative indexes count from the end.
JavaScript Strings · tutorial
JavaScript String Methods · tutorial