JavaScript String

Creating Strings

1. Using Double Quotes

const string1 = “Hello, World!”;

2. Using Single Quotes

const string2 = ‘Hello, World!’;

Common String Methods

1. length Property : Returns the length of the string.

const str = “Hello, World!”;

console.log(str.length);
// Output: 13

2. charAt(index) : Returns the character at the specified index.

const str = “Hello, World!”;

console.log(str.charAt(0));
// Output: H

3. indexOf(searchValue) : Returns the index of the first occurrence of the specified value, or -1 if not found.

const str = “Hello, World!”;

console.log(str.indexOf(“World”));
// Output: 7

console.log(str.indexOf(“world”));
// Output: -1

4. lastIndexOf(searchValue) : Returns the index of the last occurrence of the specified value, or -1 if not found.

const str = “Hello, World! Hello!”;

console.log(str.lastIndexOf(“Hello”));
// Output: 14

5. includes(searchValue) : Returns true if the string contains the specified value, otherwise false.

const str = “Hello, World!”;

console.log(str.includes(“World”));
// Output: true

console.log(str.includes(“world”));
 // Output: false

6. startsWith(searchValue) : Returns true if the string starts with the specified value, otherwise false.

const str = “Hello, World!”;

console.log(str.startsWith(“Hello”));
// Output: true

console.log(str.startsWith(“World”));
// Output: false

7. endsWith(searchValue) : Returns true if the string ends with the specified value, otherwise false.

const str = “Hello, World!”;

console.log(str.endsWith(“World!”));
// Output: true

console.log(str.endsWith(“Hello”)); 
// Output: false

8. substring(start, end) : Returns the part of the string between the start and end indexes.

const str = “Hello, World!”;

console.log(str.substring(0, 5));
// Output: Hello

9. slice(start, end) : Similar to substring but also supports negative indices.

const str = “Hello, World!”;

console.log(str.slice(0, 5)); 
// Output: Hello

console.log(str.slice(-6, -1));
// Output: World

10. toLowerCase() : Returns the string converted to lowercase.

const str = “Hello, World!”;

console.log(str.toLowerCase());
// Output: hello, world!

11. toUpperCase() : Returns the string converted to uppercase.

const str = “Hello, World!”;

console.log(str.toUpperCase());
// Output: HELLO, WORLD!

12. trim() : Removes whitespace from both ends of the string.

const str = ”   Hello, World!   “;

console.log(str.trim());
// Output: Hello, World!

13. replace(searchValue, replaceValue) : Returns a new string with some or all matches of a pattern replaced by a replacement.

const str = “Hello, World!”;

const newStr = str.replace(“World”, “Universe”);

console.log(newStr);
// Output: Hello, Universe!

14. split(separator) : Splits a string into an array of substrings using the specified separator.

const str = “Hello, World!”;

const arr = str.split(“, “);

console.log(arr);
// Output: [“Hello”, “World!”]

15. concat() : Merges or combine multiple entities into a single one.

const string1 = “Hello”;

const string2 = “World”;

const combinedString = string1.concat(” “, string2, “!”); 
// Output: combinedString will be “Hello World!”