1. length Property

The length property returns the length of a string.

let str = "Hello, world!";
let length = str.length;
console.log(length);  // Output: 13

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2. toUpperCase() Method

The toUpperCase() method converts a string to uppercase letters.

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

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3. includes() Method

The includes() method checks if a string contains a specified substring.

let str = "Hello, world!";
let hasHello = str.includes("Hello");
console.log(hasHello);  // Output: true

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4. slice() Method

The slice() method extracts a part of a string and returns a new string.

let str = "Hello, world!";
let slicedStr = str.slice(0, 5);
console.log(slicedStr);  // Output: "Hello"

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5. replace() Method

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

let str = "Hello, world!";
let newStr = str.replace("world", "JavaScript");
console.log(newStr);  // Output: "Hello, JavaScript!"

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6. charAt() Method

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

let str = "Hello, world!";
let char = str.charAt(1);
console.log(char);  // Output: "e"

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