Web/JavaScript/Reference/Global objects/String/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  '

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);
*/

Specifications

Specification
ECMAScript (ECMA-262)The definition of ' String.prototype.trimStart' in that specification.

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile						Server
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet	Node.js
`trimStart`	Chrome 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 No	Opera Full support 53 Full support 53 Full support 15 Alternate Name' Alternate Name' Uses the non-standard name: `trimLeft`	Safari Full support 12	WebView 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 14 Alternate Name' Alternate Name' Uses the non-standard name: `trimLeft`	Safari iOS Full support 12	Samsung 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.