JavaScript String Methods

String methods help you work with and manipulate text. It is important to remember that all string methods return a new string. They do not modify the original string, as strings in JavaScript are immutable.

Extracting String Parts

There are three common methods for extracting a part of a string:

1. slice(start, end)

Extracts a part of a string and returns the extracted part in a new string.

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

2. substring(start, end)

Similar to slice(), but it cannot accept negative indexes.

let str = "Hello World";
console.log(str.substring(0, 5)); // Result: "Hello"

Changing Case

You can easily convert a string to uppercase or lowercase using these methods:

let text = "Hello World!";
let upper = text.toUpperCase(); // "HELLO WORLD!"
let lower = text.toLowerCase(); // "hello world!"

Replacing Content

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

let message = "Please visit Microsoft!";
let newMsg = message.replace("Microsoft", "RedoHub"); 

console.log(newMsg); // "Please visit RedoHub!"

Trimming and Cleaning

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

let text = "      Hello World!      ";
let clean = text.trim(); 

console.log(clean); // "Hello World!"

Converting to an Array

A string can be converted into an array with the split() method.

let csv = "Red,Blue,Green";
let colors = csv.split(","); // ["Red", "Blue", "Green"]

Extracting Characters

You can get specific characters from a string using charAt() or property access [].

let text = "HELLO";
console.log(text.charAt(0)); // "H"
console.log(text[1]);        // "E"

Key Points to Remember

• String methods do not change the original string
• Use slice() or substring() to get parts of a string
• replace() helps swap text, but usually only for the first match
• trim() is essential for cleaning user input spaces
• split() is the way to turn a string into a usable array