JavaScript String Methods

Strings are texts that help in holding data that can be represented. A JavaScript string stores a series of characters like “GeeksforGeeks”. A string can be any text inside double or single quotes.

JavaScript String Methods and Property: String methods and properties are important to perform any operation on the given string, the string search methods have a separate article for better understanding. Below we have described a few important methods with the proper example code.

• String length Property

• String slice() Method
• String substring() Method
• String substr() Method
• String replace() Method
• String replaceAll() Method
• String toUpperCase() Method
• String toLowerCase() Method
• String concat() Method

• String trim() Method
• String trimStart() Method
• String trimEnd() Method
• String padStart() Method
• String padEnd() Method
• String charAt() Method
• String charCodeAt() Method
• String split() Method

String indexes start from 0. The first character is in position 0 and the second in 1 and the same follows. We can call any of the pre-defined methods of JavaScript as it automatically converts from string primitive to objects.

Example:

 let gfg= "geeksforgeeks";

JavaScript String length Property: This property returns the number of characters present in the string. In the case of an array, this property returns the number of elements present in the array.

Example: This example describes the JavaScript String Length property.

JavaScript

<script>
    // JavaScript to illustrate length property
    function func() {

        // length property for string
        console.log("GFG".length)
    }
    func();
</script>

Output:

3

JavaScript slice(startIndex, endIndex) Method: This method extracts a part of the string based on the given stating-index and ending-index and returns a new string.

Example: This example describes the JavaScript String slice() method.

javascript

let A = 'Geeks for Geeks';
b = A.slice(0,5);
c = A.slice(6,9);
d = A.slice(10);

console.log(b);
console.log(c);
console.log(d);

Output:

Geeks
for
Geeks

JavaScript substring(startIndex, endIndex) Method: This method returns the part of the given string from the start index to the end index. Indexing start from zero (0).

Javascript

let str = "Mind, Power, Soul";
let part = str.substring(6, 11);
console.log(part);

Output:

Power

JavaScript substr(start, length) Method: This method returns the specified number of characters from the specified index from the given string. It basically extracts a part of the original string.

Javascript

let str = "Mind, Power, Soul";
let part = str.substr(6, 5);
console.log(part);

Power

JavaScript replace(replaceValue, replaceWithValue) Method: This method replaces a part of the given string with another string or a regular expression. The original string will remain unchanged.

Javascript

let str = "Mind, Power, Soul";
let part = str.replace("Power", "Space");
console.log(part);

Output:

Mind, Space, Soul

JavaScript replaceAll(regexp | substr , newSubstr | function) Method: This method returns a new string after replacing all the matches of a string with a specified string or a regular expression. The original string is left unchanged after this operation.

Javascript

let str = "Mind, Power, Power,  Soul";
let part = str.replaceAll("Power", "Space");
console.log(part);

Output:

Mind, Space, Space,  Soul

JavaScript toUpperCase(stringVariable) Method: This method converts all the characters present in the String to upper case and returns a new String with all characters in upper case. This method accepts single parameter stringVariable string that you want to convert in upper case.

Example: This example describes the JavaScript String toUpperCase() method.

javascript

let gfg = 'GFG '
let geeks = 'stands-for-GeeksforGeeks';

console.log(geeks.toUpperCase(geeks)) ;

Output:

STANDS-FOR-GEEKSFORGEEKS

JavaScript toLowerCase(stringVariable) Method: This method converts all the characters present in the so lowercase and returns a new string with all the characters in lowercase.

tring t

Example: This example describes the JavaScript String toLowerCase() method.

javascript

let gfg = 'GFG ';
let geeks = 'stands-for-GeeksforGeeks';

console.log(geeks.toLowerCase(geeks));

Output:

stands-for-geeksforgeeks

JavaScript concat(objectOfString) Method: This method combines the text of two strings and returns a new combined or joined string. To concatenate two strings, we use concat() method on one object of string and send another object of string as a parameter. This method accepts one argument. The variable contains text in double quotes or single quotes.

Example: This example describes the JavaScript String concat() method.

javascript

let gfg = 'GFG ';
let geeks = 'stands for GeeksforGeeks';

// Accessing concat method on an object
// of String passing another object
// as a parameter
console.log(gfg.concat(geeks));

Output:

GFG stands for GeeksforGeeks

JavaScript trim() Method: This method is used to remove either white spaces from the given string. This method returns a new string with removed white spaces. This method is called on a String object. This method doesn’t accept any parameter.

Example: This example describes the JavaScript String trim() method.

javascript

let gfg = 'GFG    ';
let geeks = 'stands-for-GeeksforGeeks';

// Storing new object of string
// with removed white spaces
let newGfg = gfg.trim();

// Old length
console.log(gfg.length);

// New length
console.log(newGfg.length)

Output:

7
3

JavaScript trimStart() Method: This method removes whitespace from the beginning of a string. The value of the string is not modified in any manner, including any whitespace present after the string.

Javascript

let str = "  Soul";
console.log(str)
let part = str.trimStart();
console.log(part);

Output:

  Soul
Soul

JavaScript trimEnd() Method: This method removes white space from the end of a string. The value of the string is not modified in any manner, including any white-space present before the string.

Javascript

let str = "Soul  ";
console.log(str)
let part = str.trimEnd();
console.log(part);

Output:

Soul    
Soul

JavaScript padStart() Method: This method pad a string with another string until it reaches the given length. The padding is applied from the left end of the string.

Javascript

let stone = "Soul";
stone = stone.padStart(9,"Mind ");
console.log(stone);

Output:

Mind Soul

JavaScript padEnd() Method: This method pad a string with another string until it reaches the given length. The padding is applied from the right end of the string.

Javascript

let stone = "Soul";
stone = stone.padEnd(10," Power");
console.log(stone);

Output:

Soul Power

JavaScript charAt(indexOfCharacter) Method: This method returns the character at the specified index. String in JavaScript has zero-based indexing.

Example: This example describes the JavaScript string charAt() method.

javascript

let gfg = 'GeeksforGeeks';
let geeks = 'GfG is the best platform to learn and\n'+
'experience Computer Science.';

// Print the string as it is
console.log(gfg);

console.log(geeks);

// As string index starts from zero
// It will return first character of string
console.log(gfg.charAt(0));

console.log(geeks.charAt(5));

Output:

GeeksforGeeks
GfG is the best platform to learn 
and experience Computer Science.
G
s

JavaScript charCodeAt(indexOfCharacter) Method: This method returns a number that represents the Unicode value of the character at the specified index. This method accepts one argument.

Example: This example describes the JavaScript String charCodeAt() Method.

javascript

let gfg = 'GeeksforGeeks';
let geeks = 'GfG is the best platform\n\
to learn and experience\n\
Computer Science.';

// Return a number indicating Unicode
// value of character at index 0 ('G')
console.log(gfg.charCodeAt(0));
console.log(geeks.charCodeAt(5));

Output:

71
115

JavaScript split(character) Method: This method splits the string into an array of sub-strings. This method returns an array. This method accepts a single parameter character on which you want to split the string.

Example: This example describes the JavaScript String split() method.

javascript

let gfg = 'GFG '
let geeks = 'stands-for-GeeksforGeeks'

// Split string on '-'.
console.log(geeks.split('-'))

Output:

['stands', 'for', 'GeeksforGeeks']