String.prototype.trimStart()

The trimStart() method removes whitespace from the beginning of a string. trimLeft() is an alias of this method.

Syntax

str.trimStart();
str.trimLeft();

Return value

A new string representing the calling string stripped of whitespace from its beginning (left end).

Description

The trimStart() / trimLeft() methods return the string stripped of whitespace from its left end. trimLeft() or trimStart() do not affect the value of the string itself.

Aliasing

For consistency with functions like String.prototype.padStart the standard method name is trimStart. However, for web compatibility reasons, trimLeft remains as an alias to trimStart. In some engines this means:

String.prototype.trimLeft.name === "trimStart";

Examples

Using trimStart()

The following example displays the lowercase string 'foo  ':

var str = '   foo  ';

console.log(str.length); // 8

str = str.trimStart();
console.log(str.length); // 5
console.log(str);        // 'foo  '

Specifications

Specification Status Comment
ECMAScript 2019 trimStart() definition Stage 4 Part of ES2019

Browser compatibility

Update compatibility data on GitHub
DesktopMobileServer
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung InternetNode.js
trimStartChrome Full support 66
Full support 66
Full support 4
Alternate Name
Alternate Name Uses the non-standard name: trimLeft
Edge Full support 12
Alternate Name
Full support 12
Alternate Name
Alternate Name Uses the non-standard name: trimLeft
Firefox Full support 61
Full support 61
Full support 3.5
Alternate Name
Alternate Name Uses the non-standard name: trimLeft
IE No support NoOpera Full support 53
Full support 53
Full support Yes
Alternate Name
Alternate Name Uses the non-standard name: trimLeft
Safari Full support 12WebView Android Full support 66
Full support 66
Full support ≤37
Alternate Name
Alternate Name Uses the non-standard name: trimLeft
Chrome Android Full support 66
Full support 66
Full support 18
Alternate Name
Alternate Name Uses the non-standard name: trimLeft
Firefox Android Full support 61
Full support 61
Full support 4
Alternate Name
Alternate Name Uses the non-standard name: trimLeft
Opera Android Full support 47
Full support 47
Full support Yes
Alternate Name
Alternate Name Uses the non-standard name: trimLeft
Safari iOS Full support 12Samsung Internet Android Full support 9.0
Full support 9.0
Full support 1.0
Alternate Name
Alternate Name Uses the non-standard name: trimLeft
nodejs Full support 10.0.0
Full support 10.0.0
Full support 0.12
Alternate Name
Alternate Name Uses the non-standard name: trimLeft

Legend

Full support  
Full support
No support  
No support
Uses a non-standard name.
Uses a non-standard name.

Polyfill

//https://github.com/FabioVergani/js-Polyfill_String-trimStart

(function(w){
    var String=w.String, Proto=String.prototype;

    (function(o,p){
        if(p in o?o[p]?false:true:true){
            var r=/^\s+/;
            o[p]=o.trimLeft||function(){
                return this.replace(r,'')
            }
        }
    })(Proto,'trimStart');

})(window); 


/*
ES6:
(w=>{
    const String=w.String, Proto=String.prototype;

    ((o,p)=>{
        if(p in o?o[p]?false:true:true){
            const r=/^\s+/;
            o[p]=o.trimLeft||function(){
                return this.replace(r,'')
            }
        }
    })(Proto,'trimStart');

})(window);
*/

See also