Javascript Strings

JavaScript Strings

In JavaScript, Strings are sequences of characters used to represent text. They can be created using single (‘ ‘), double (” “), or backticks (“`) for template literals.

let singleQuoteString = ‘Hello’;

let doubleQuoteString = “World”;

let templateString = `Hello, ${singleQuoteString}!`;

Strings in JavaScript are immutable, meaning their values cannot be changed once created. You can, however, create a new string from existing ones.

JavaScript String Methods

JavaScript provides numerous built-in methods to manipulate strings: length – Returns the length of the string.

let greeting = “Hello”;

console.log(greeting.length); // Outputs: 5

1. toUpperCase() – Converts the string to uppercase.

console.log(greeting.toUpperCase()); // Outputs: HELLO

2. toLowerCase() – Converts the string to lowercase.

console.log(greeting.toLowerCase()); // Outputs: hello

3. slice(start, end) – Extracts a part of the string from start to end.

let sliced = greeting.slice(0, 2); // Outputs: He

4. replace(search, replaceWith) – Replaces a specified string with another.

console.log(greeting.replace(“Hello”, “Hi”)); // Outputs: Hi

5. concat() – Concatenates multiple strings.

let world = “World”;

console.log(greeting.concat(” “, world)); // Outputs: Hello World

6. trim() – Removes whitespace from both ends.

let spacedString = ” Hi “;

console.log(spacedString.trim()); // Outputs: Hi

JavaScript String Search

JavaScript provides methods to search within strings:

1. indexOf() – Returns the index of the first occurrence of a specified text.

console.log(greeting.indexOf(“e”)); // Outputs: 1

2. lastIndexOf() – Returns the last occurrence.

console.log(greeting.lastIndexOf(“l”)); // Outputs: 3

3. search() – Similar to indexOf but can take regular expressions.

console.log(greeting.search(“e”)); // Outputs: 1

4. includes() – Checks if a string contains a specified value.

console.log(greeting.includes(“H”)); // Outputs: true

5. startsWith() and endsWith() – Checks if the string starts or ends with a specified text.

console.log(greeting.startsWith(“H”)); // Outputs: true

console.log(greeting.endsWith(“o”)); // Outputs: true

JavaScript Template Strings

Template strings allow embedding expressions within strings using ${expression} syntax:

let name = “Jane”;

let message = `Hello, ${name}!`; // Outputs: Hello, Jane!

They’re especially useful for multiline strings:

let text = `This is a

multiline string.`;

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Javascript Strings