The padStart()
method of String
values pads this string with another string (multiple times, if needed) until the resulting string reaches the given length. The padding is applied from the start of this string.
The padStart()
method of String
values pads this string with another string (multiple times, if needed) until the resulting string reaches the given length. The padding is applied from the start of this string.
padStart(targetLength) padStart(targetLength, padString)
targetLength
The length of the resulting string once the current str
has been padded. If the value is less than or equal to str.length
, then str
is returned as-is.
padString
Optional
The string to pad the current str
with. If padString
is too long to stay within the targetLength
, it will be truncated from the end. The default value is the unicode "space" character (U+0020).
A String
of the specified targetLength
with padString
applied from the start.
"abc".padStart(10); // " abc" "abc".padStart(10, "foo"); // "foofoofabc" "abc".padStart(6, "123465"); // "123abc" "abc".padStart(8, "0"); // "00000abc" "abc".padStart(1); // "abc"
// 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)); // "00123"
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padStart |
57 | 15 | 48 | 44 | 10 | 57 | 48 | 43 | 10 | 7.0 | 57 | 1.0 | 8.0.0 |
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https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/padStart