String.prototype.trimStart()
The trimStart()
method removes whitespace from the beginning of a string and returns a new string, without modifying the original string. trimLeft()
is an alias of this method.
Try it
Syntax
js
trimStart()
trimLeft()
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 padEnd()
, 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:
js
String.prototype.trimLeft.name === "trimStart";
Examples
Using trimStart()
The following example trims whitespace from the start of str
, but not from its end.
js
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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