String.prototype.trimStart()
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.
The trimStart()
method of String
values removes whitespace from the beginning of this string and returns a new string, without modifying the original string. trimLeft()
is an alias of this method.
Try it
Syntax
trimStart()
trimLeft()
Parameters
None.
Return value
A new string representing str
stripped of whitespace from its beginning (left side). Whitespace is defined as white space characters plus line terminators.
If the beginning of str
has no whitespace, a new string is still returned (essentially a copy of str
).
Aliasing
After trim()
was standardized, engines also implemented the non-standard method trimLeft
. However, for consistency with padStart()
, when the method got standardized, its name was chosen as trimStart
. For web compatibility reasons, trimLeft
remains as an alias to trimStart
, and they refer to the exact same function object. In some engines this means:
String.prototype.trimLeft.name === "trimStart";
Examples
Using trimStart()
The following example trims whitespace from the start of str
, but not from its end.
let str = " foo ";
console.log(str.length); // 8
str = str.trimStart();
console.log(str.length); // 5
console.log(str); // 'foo '
Specifications
Specification |
---|
ECMAScript Language Specification # sec-string.prototype.trimstart |
Browser compatibility
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