JavaScript

In JavaScript, strings are a commonly used data type, and JavaScript provides many built-in string methods to manipulate them. These methods help you perform operations like changing the case, extracting parts of a string, replacing text, and more.

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✅ What is a String Method?

A string method is a function that can be called on a string to perform specific actions. These are very useful for working with text data in your web applications.

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🔹 1. .length – Returns the length of a string

let text = "Hello World!";
console.log(text.length); // Output: 12

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🔹 2. .toUpperCase() – Converts to uppercase

let text = "hello";
console.log(text.toUpperCase()); // Output: "HELLO"

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🔹 3. .toLowerCase() – Converts to lowercase

let text = "HELLO";
console.log(text.toLowerCase()); // Output: "hello"

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🔹 4. .slice(start, end) – Extracts a section of the string

let text = "JavaScript";
console.log(text.slice(0, 4)); // Output: "Java"

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🔹 5. .substring(start, end) – Similar to slice, but doesn’t accept negative values

let text = "JavaScript";
console.log(text.substring(4, 10)); // Output: "Script"

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🔹 6. .replace(oldValue, newValue) – Replaces first occurrence

let text = "I love JavaScript!";
console.log(text.replace("JavaScript", "Coding")); // Output: "I love Coding!"

⚠️ Note: replace() is case-sensitive. Use replaceAll() or regex for replacing multiple or case-insensitive matches.

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🔹 7. .trim() – Removes extra whitespace from both ends

let text = "   Hello World!   ";
console.log(text.trim()); // Output: "Hello World!"

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🔹 8. .charAt(index) – Returns the character at a specific index

let text = "Hello";
console.log(text.charAt(1)); // Output: "e"

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🔹 9. .split(separator) – Splits the string into an array

let text = "Apple, Banana, Mango";
let fruits = text.split(", ");
console.log(fruits); // Output: ["Apple", "Banana", "Mango"]

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✨ Bonus: Chaining Methods

You can also chain string methods together:

let result = "   hello world!   ".trim().toUpperCase();
console.log(result); // Output: "HELLO WORLD!"

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🧠 Summary

Method	Description
.length	Returns string length
.toUpperCase()	Converts string to uppercase
.toLowerCase()	Converts string to lowercase
.slice()	Extracts part of the string
.replace()	Replaces part of the string
.trim()	Removes spaces from both ends
.charAt()	Gets character at a position
.split()	Converts string into array

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