JavaScript String Methods

JavaScript strings are a sequence of characters, like words or sentences. They help us manage text in programs. JavaScript gives us many tools (called “methods”) to work with strings. These methods allow us to get parts of strings, combine them, change their appearance (like uppercase or lowercase), and much more.

Here’s the List of JavaScript String Methods:

Method	Definition	Example Code & Output
charAt()	Returns the character at a specific index in a string.	let str = “Justin Bieber”; console.log(str.charAt(2)); // Output: “s”
charCodeAt()	Returns the Unicode of the character at a specific index.	let str = “Justin Bieber”; console.log(str.charCodeAt(2)); // Output: 115 (Unicode of ‘s’)
concat()	Combines two or more strings and returns a new string.	let str1 = “Justin “; let str2 = “Bieber”; console.log(str1.concat(str2)); // Output: “Justin Bieber”
endsWith()	Checks if a string ends with a specified string/characters.	let str = “Justin Bieber”; console.log(str.endsWith(“Bieber”)); // Output: true
includes()	Checks if a string contains the specified string/characters.	let str = “Justin Bieber”; console.log(str.includes(“Bieber”)); // Output: true
indexOf()	Returns the index of the first occurrence of a substring.	let str = “Justin Bieber”; console.log(str.indexOf(“Bieber”)); // Output: 7
lastIndexOf()	Returns the index of the last occurrence of a substring.	let str = “Justin Bieber Bieber”; console.log(str.lastIndexOf(“Bieber”)); // Output: 13
match()	Retrieves matches of a string against a regular expression.	let str = “Justin123Bieber”; console.log(str.match(/\d+/)); // Output: [“123”]
matchAll()	Returns an iterator of all matched results.	let str = “Justin Bieber”; console.log([…str.matchAll(/i/g)]); // Output: [[“i”], [“i”]]
padStart()	Pads the current string with another string at the start.	let str = “Bieber”; console.log(str.padStart(10, “Justin “)); // Output: “Justin Bieber”
padEnd()	Pads the current string with another string at the end.	let str = “Justin”; console.log(str.padEnd(12, ” Bieber”)); // Output: “Justin Bieber”
repeat()	Returns a new string with a specified number of copies.	let str = “Justin “; console.log(str.repeat(3)); // Output: “Justin Justin Justin ”
replace()	Replaces a substring with a new substring.	Table Bodylet str = “Justin Bieber”; console.log(str.replace(“Bieber”, “Timberlake”)); // Output: “Justin Timberlake”
replaceAll()	Replaces all matches of a substring with a new substring.	let str = “Justin Bieber Bieber”; console.log(str.replaceAll(“Bieber”, “Timberlake”)); // Output: “Justin Timberlake Timberlake”
search()	Searches for a match between a string and a regular expression.	let str = “Justin Bieber”; console.log(str.search(“Bieber”)); // Output: 7
slice()	Extracts a part of a string and returns it as a new string.	let str = “Justin Bieber”; console.log(str.slice(7)); // Output: “Bieber”
split()	Splits a string into an array of substrings.	let str = “Justin Bieber”; console.log(str.split(” “)); // Output: [“Justin”, “Bieber”]
startsWith()	Checks if a string starts with the specified string.	let str = “Justin Bieber”; console.log(str.startsWith(“Justin”)); // Output: true
substring()	Extracts the characters between two indices.	let str = “Justin Bieber”; console.log(str.substring(0, 6)); // Output: “Justin”
toLowerCase()	Converts a string to lowercase letters.	let str = “Justin Bieber”; console.log(str.toLowerCase()); // Output: “justin bieber”
toUpperCase()	Converts a string to uppercase letters.	let str = “Justin Bieber”; console.log(str.toUpperCase()); // Output: “JUSTIN BIEBER”
trim()	Removes whitespace from both ends of a string.	let str = ” Justin Bieber “; console.log(str.trim()); // Output: “Justin Bieber”
trimStart()	Removes whitespace from the beginning of a string.	let str = ” Justin”; console.log(str.trimStart()); // Output: “Justin”
trimEnd()	Removes whitespace from the end of a string.	let str = “Bieber “; console.log(str.trimEnd()); // Output: “Bieber”
valueOf()	Returns the primitive value of a String object.	let str = new String(“Justin Bieber”); console.log(str.valueOf()); // Output: “Justin Bieber”
localeCompare()	Compares two strings in the current locale.	let str1 = “Justin”; let str2 = “Bieber”; console.log(str1.localeCompare(str2)); // Output: 1 (because “Justin” > “Bieber”)
fromCharCode()	Converts Unicode values to characters.	console.log(String.fromCharCode(74, 117, 115, 116, 105, 110)); // Output: “Justin”
normalize()	Returns the Unicode Normalization Form of a string.	let str = “Bieber\u0301”; console.log(str.normalize(“NFC”)); // Output: “Biéber” (normalized accent)

Key Notes

• substr() has been deprecated and is replaced by slice() or substring().
• Methods like charAt(), charCodeAt(), replace(), and match() are among the most commonly used for basic string operations.

Remember

JavaScript string methods help you manipulate text, whether changing the case of letters, replacing parts of text, or extracting specific sections. These simple tools are useful for all types of programming tasks that involve text.

Course Video

YouTube Reference :

1) JavaScript String Methods Tutorial in Hindi / Urdu
2) JavaScript String Methods – II Tutorial in Hindi / Urdu
3) JavaScript String methods | JavaScript Full Tutorial in English

Practice Scenarios

Scenario 1: String Methods - Changing Case

Objective: Demonstrate the use of string methods to change the case of a string to uppercase and lowercase.

Expected Output: A console output showing the original string and its uppercase and lowercase versions.