JavaScript String Methods


JavaScript String Length

The length property returns the length of a string:

Example

let text = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
let length = text.length;
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Extracting String Characters

There are 4 methods for extracting string characters:

  • The at(position) Method
  • The charAt(position) Method
  • The charCodeAt(position) Method
  • Using property access [] like in arrays

JavaScript String charAt()

The charAt() method returns the character at a specified index (position) in a string:

Example

let text = "HELLO WORLD";
let char = text.charAt(0);
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JavaScript String charCodeAt()

The charCodeAt() method returns the code of the character at a specified index in a string:

The method returns a UTF-16 code (an integer between 0 and 65535).

Example

let text = "HELLO WORLD";
let char = text.charCodeAt(0);
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JavaScript String at()

ES2022 intoduced the string method at():

Examples

Get the third letter of name:

const name = "W3Schools";
let letter = name.at(2);
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Get the third letter of name:

const name = "W3Schools";
let letter = name[2];
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The at() method returns the character at a specified index (position) in a string.

The at() method returns the same as carAt().

The at() method is supported in all modern browsers since March 2022:

Note

The at() method is a new addition to JavaScript.

It allows the use of negative indexes while charAt() do not.

Now you can use myString.at(-2) instead of charAt(myString.length-2).

Browser Support

at() is an ES2022 feature.

JavaScript 2022 (ES2022) is supported in all modern browsers since March 2023:

Chrome 94 Edge 94 Firefox 93 Safari 16.4 Opera 79
Sep 2021 Sep 2021 Oct 2021 Mar 2023 Oct 2021

Property Access [ ]

Example

let text = "HELLO WORLD";
let char = text[0];
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Note

Property access might be a little unpredictable:

  • It makes strings look like arrays (but they are not)
  • If no character is found, [ ] returns undefined, while charAt() returns an empty string.
  • It is read only. str[0] = "A" gives no error (but does not work!)

Example

let text = "HELLO WORLD";
text[0] = "A";    // Gives no error, but does not work
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Extracting String Parts

There are 3 methods for extracting a part of a string:

  • slice(start, end)
  • substring(start, end)
  • substr(start, length)

JavaScript String slice()

slice() extracts a part of a string and returns the extracted part in a new string.

The method takes 2 parameters: start position, and end position (end not included).

Example

Slice out a portion of a string from position 7 to position 13:

let text = "Apple, Banana, Kiwi";
let part = text.slice(7, 13);
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Note

JavaScript counts positions from zero.

First position is 0.

Second position is 1.

Examples

If you omit the second parameter, the method will slice out the rest of the string:

let text = "Apple, Banana, Kiwi";
let part = text.slice(7);
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If a parameter is negative, the position is counted from the end of the string:

let text = "Apple, Banana, Kiwi";
let part = text.slice(-12);
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This example slices out a portion of a string from position -12 to position -6:

let text = "Apple, Banana, Kiwi";
let part = text.slice(-12, -6);
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JavaScript String substring()

substring() is similar to slice().

The difference is that start and end values less than 0 are treated as 0 in substring().

Example

let str = "Apple, Banana, Kiwi";
let part = str.substring(7, 13);
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If you omit the second parameter, substring() will slice out the rest of the string.


JavaScript String substr()

substr() is similar to slice().

The difference is that the second parameter specifies the length of the extracted part.

Example

let str = "Apple, Banana, Kiwi";
let part = str.substr(7, 6);
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If you omit the second parameter, substr() will slice out the rest of the string.

Example

let str = "Apple, Banana, Kiwi";
let part = str.substr(7);
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If the first parameter is negative, the position counts from the end of the string.

Example

let str = "Apple, Banana, Kiwi";
let part = str.substr(-4);
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Converting to Upper and Lower Case

A string is converted to upper case with toUpperCase():

A string is converted to lower case with toLowerCase():


JavaScript String toUpperCase()

Example

let text1 = "Hello World!";
let text2 = text1.toUpperCase();
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JavaScript String toLowerCase()

Example

let text1 = "Hello World!";       // String
let text2 = text1.toLowerCase();  // text2 is text1 converted to lower
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JavaScript String concat()

concat() joins two or more strings:

Example

let text1 = "Hello";
let text2 = "World";
let text3 = text1.concat(" ", text2);
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The concat() method can be used instead of the plus operator. These two lines do the same:

Example

text = "Hello" + " " + "World!";
text = "Hello".concat(" ", "World!");

Note

All string methods return a new string. They don't modify the original string.

Formally said:

Strings are immutable: Strings cannot be changed, only replaced.


JavaScript String trim()

The trim() method removes whitespace from both sides of a string:

Example

let text1 = "      Hello World!      ";
let text2 = text1.trim();
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JavaScript String trimStart()

ECMAScript 2019 added the String method trimStart() to JavaScript.

The trimStart() method works like trim(), but removes whitespace only from the start of a string.

Example

let text1 = "     Hello World!     ";
let text2 = text1.trimStart();
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JavaScript String trimStart() is supported in all modern browsers since January 2020:

Chrome 66 Edge 79 Firefox 61 Safari 12 Opera 50
Apr 2018 Jan 2020 Jun 2018 Sep 2018 May 2018

JavaScript String trimEnd()

ECMAScript 2019 added the string method trimEnd() to JavaScript.

The trimEnd() method works like trim(), but removes whitespace only from the end of a string.

Example

let text1 = "     Hello World!     ";
let text2 = text1.trimEnd();
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JavaScript String trimEnd() is supported in all modern browsers since January 2020:

Chrome 66 Edge 79 Firefox 61 Safari 12 Opera 50
Apr 2018 Jan 2020 Jun 2018 Sep 2018 May 2018

JavaScript String Padding

ECMAScript 2017 added two new string methods to JavaScript: padStart() and padEnd() to support padding at the beginning and at the end of a string.


JavaScript String padStart()

The padStart() method pads a string from the start.

It pads a string with another string (multiple times) until it reaches a given length.

Examples

Pad a string with "0" until it reaches the length 4:

let text = "5";
let padded = text.padStart(4,"0");
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Pad a string with "x" until it reaches the length 4:

let text = "5";
let padded = text.padStart(4,"x");
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Note

The padStart() method is a string method.

To pad a number, convert the number to a string first.

See the example below.

Example

let numb = 5;
let text = numb.toString();
let padded = text.padStart(4,"0");
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Browser Support

padStart() is an ECMAScript 2017 feature.

ES2017 is supported in all modern browsers since September 2017:

Chrome 58 Edge 15 Firefox 52 Safari 11 Opera 45
Apr 2017 Apr 2017 Mar 2017 Sep 2017 May 2017

padStart() is not supported in Internet Explorer.


JavaScript String padEnd()

The padEnd() method pads a string from the end.

It pads a string with another string (multiple times) until it reaches a given length.

Examples

let text = "5";
let padded = text.padEnd(4,"0");
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let text = "5";
let padded = text.padEnd(4,"x");
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Note

The padEnd() method is a string method.

To pad a number, convert the number to a string first.

See the example below.

Example

let numb = 5;
let text = numb.toString();
let padded = text.padEnd(4,"0");
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Browser Support

padEnd() is an ECMAScript 2017 feature.

ES2017 is supported in all modern browsers since September 2017:

Chrome 58 Edge 15 Firefox 52 Safari 11 Opera 45
Apr 2017 Apr 2017 Mar 2017 Sep 2017 May 2017

padEnd() is not supported in Internet Explorer.


JavaScript String repeat()

The repeat() method returns a string with a number of copies of a string.

The repeat() method returns a new string.

The repeat() method does not change the original string.

Examples

Create copies of a text:

let text = "Hello world!";
let result = text.repeat(2);
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let text = "Hello world!";
let result = text.repeat(4);
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Syntax

string.repeat(count)

Parameters

Parameter Description
countRequired.
The number of copies wanted.

Return Value

Type Description
StringA new string containing the copies.

Browser Support

repeat() is an ES6 feature (JavaScript 2015).

ES6 is fully supported in all modern browsers since June 2017:

Chrome 51 Edge 15 Firefox 54 Safari 10 Opera 38
May 2016 Apr 2017 Jun 2017 Sep 2016 Jun 2016

repeat() is not supported in Internet Explorer.


Replacing String Content

The replace() method replaces a specified value with another value in a string:

Example

let text = "Please visit Microsoft!";
let newText = text.replace("Microsoft", "W3Schools");
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Note

The replace() method does not change the string it is called on.

The replace() method returns a new string.

The replace() method replaces only the first match

If you want to replace all matches, use a regular expression with the /g flag set. See examples below.

By default, the replace() method replaces only the first match:

Example

let text = "Please visit Microsoft and Microsoft!";
let newText = text.replace("Microsoft", "W3Schools");

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By default, the replace() method is case sensitive. Writing MICROSOFT (with upper-case) will not work:

Example

let text = "Please visit Microsoft!";
let newText = text.replace("MICROSOFT", "W3Schools");

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To replace case insensitive, use a regular expression with an /i flag (insensitive):

Example

let text = "Please visit Microsoft!";
let newText = text.replace(/MICROSOFT/i, "W3Schools");

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Note

Regular expressions are written without quotes.

To replace all matches, use a regular expression with a /g flag (global match):

Example

let text = "Please visit Microsoft and Microsoft!";
let newText = text.replace(/Microsoft/g, "W3Schools");

Try it Yourself »

Note

You will learn a lot more about regular expressions in the chapter JavaScript Regular Expressions.


JavaScript String ReplaceAll()

In 2021, JavaScript introduced the string method replaceAll():

Example

text = text.replaceAll("Cats","Dogs");
text = text.replaceAll("cats","dogs");
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The replaceAll() method allows you to specify a regular expression instead of a string to be replaced.

If the parameter is a regular expression, the global flag (g) must be set, otherwise a TypeError is thrown.

Example

text = text.replaceAll(/Cats/g,"Dogs");
text = text.replaceAll(/cats/g,"dogs");
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Note

replaceAll() is an ES2021 feature.

replaceAll() does not work in Internet Explorer.


Converting a String to an Array

If you want to work with a string as an array, you can convert it to an array.

JavaScript String split()

A string can be converted to an array with the split() method:

Example

text.split(",")    // Split on commas
text.split(" ")    // Split on spaces
text.split("|")    // Split on pipe
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If the separator is omitted, the returned array will contain the whole string in index [0].

If the separator is "", the returned array will be an array of single characters:

Example

text.split("")
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Complete String Reference

For a complete String reference, go to our:

Complete JavaScript String Reference.

The reference contains descriptions and examples of all string properties and methods.

Test Yourself With Exercises

Exercise:

Convert the text into an UPPERCASE text:

let txt = "Hello World!";
txt = txt.;

Start the Exercise

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