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

const greeting = "   Hello world!   ";

console.log(greeting);
// Expected output: "   Hello world!   ";

console.log(greeting.trimStart());
// Expected output: "Hello world!   ";

Syntax

js
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.

js
let str = "   foo  ";

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

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

Specifications

Specification

ECMAScript® 2027 Language Specification
# sec-string.prototype.trimstart

Browser compatibility

Enable JavaScript to view this browser compatibility table.

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This page was last modified on Jul 10, 2025 by MDN contributors.

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Standard built-in objects
String
Constructor
1. String()
Static methods
Instance methods
Instance properties
1. length
Inheritance
Object/Function
Static methods
Static properties
Instance methods
Instance properties
1. __proto__
2. constructor