The padStart()
method pads the current string with another string (multiple times, if needed) until the resulting string reaches the given length. The padding is applied from the start of the current string.
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Syntax
str.padStart(targetLength [, padString])
Parameters
targetLength
- The length of the resulting string once the current
str
has been padded. If the value is less thanstr.length
, thenstr
is returned as-is. padString
Optional- The string to pad the current
str
with. IfpadString
is too long to stay within thetargetLength
, it will be truncated from the end. The default value is" "
(U+0020 'SPACE'
).
Return value
A String
of the specified targetLength
with padString
applied from the start.
Examples
Basic examples
'abc'.padStart(10); // " abc" 'abc'.padStart(10, "foo"); // "foofoofabc" 'abc'.padStart(6,"123465"); // "123abc" 'abc'.padStart(8, "0"); // "00000abc" 'abc'.padStart(1); // "abc"
Fixed width string number conversion
// Javascript version of: (unsigned) // printf "%0*d" width num function leftFillNum(num, targetLength) { return num.toString().padStart(targetLength, 0); } const num = 123; console.log(leftFillNum(num, 5)); // expected output: "00123"
Specifications
Specification |
---|
ECMAScript (ECMA-262) The definition of 'String.prototype.padStart' in that specification. |
Browser compatibility
The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out https://github.com/mdn/browser-compat-data and send us a pull request.
Desktop | Mobile | Server | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
padStart | Chrome Full support 57 | Edge Full support 15 | Firefox Full support 48 | IE No support No | Opera Full support 44 | Safari Full support 10 | WebView Android Full support 57 | Chrome Android Full support 57 | Firefox Android Full support 48 | Opera Android Full support 43 | Safari iOS Full support 10 | Samsung Internet Android Full support 7.0 | nodejs
Full support
8.0.0
|
Legend
- Full support
- Full support
- No support
- No support
- User must explicitly enable this feature.
- User must explicitly enable this feature.