Strings

8. Strings#

Strings are one of the most common data types in JavaScript, used to store and manipulate text. This page will introduce you to defining strings, combining them, working with quotes, using common string methods, and formatting text with template literals.

8.1. Defining Strings#

A string is a sequence of characters, such as letters, numbers, symbols, or spaces, enclosed in quotes.

JavaScript allows you to define strings using either single or double quotes.

Single quotes

let singleQuoteString = 'Hello, world!';

Double quotes**

let doubleQuoteString = "Hello, world!";

Both single and double quotes work the same way, but you should be consistent in your code.

8.2. String Concatenation#

You can combine (or concatenate) strings using the + operator.

let firstName = "Alice";
let lastName = "Johnson";
let fullName = firstName + " " + lastName;
console.log(fullName); // Prints: Alice Johnson

8.3. Nesting Quotes#

Sometimes, you need to include quotes inside a string. Use the opposite type of quote for the string and the nested quotes.

Example:

let sentence = "She said, 'JavaScript is fun!'";
console.log(sentence); // Prints: She said, 'JavaScript is fun!'

If you must use the same type of quote, use a backslash (\) to escape the nested quotes:

let sentence = 'She said, "JavaScript is fun!"';
let escapedSentence = 'It\'s a great day for coding.';
console.log(escapedSentence); // Prints: It's a great day for coding.

8.4. Useful String Methods#

JavaScript strings arecome with built-in methods for performing common tasks. Here are some examples:

Finding the Length of a String

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

Accessing Characters with Indexing

Strings are zero-indexed, meaning the first character is at position 0.

let word = "JavaScript";
console.log(word[0]); // Prints: J
console.log(word[4]); // Prints: S

Splitting Strings

You can split a string into an array of smaller strings using the split() method.

let sentence = "Learning JavaScript is fun!";
let words = sentence.split(" "); // Splits by spaces
console.log(words); // Prints: ['Learning', 'JavaScript', 'is', 'fun!']

Converting to Upper or Lower Case

let text = "JavaScript";
console.log(text.toUpperCase()); // Prints: JAVASCRIPT
console.log(text.toLowerCase()); // Prints: javascript

Finding Substrings

You can check if a string contains another string using includes().

let phrase = "I love programming!";
console.log(phrase.includes("love")); // Prints: true

8.5. Template Literals#

Template literals make working with strings easier and more powerful. They use backticks (`) instead of quotes.

Multiline Strings

let multiline = `This is
a string
on multiple lines.`;
console.log(multiline);

Embedding Expressions

You can insert variables or expressions directly into a string using ${}.

let name = "Alice";
let age = 16;
let message = `My name is ${name} and I am ${age} years old.`;
console.log(message); // Prints: My name is Alice and I am 16 years old.

Including Quotes Without Escaping

let quote = `She said, "JavaScript is awesome!"`;
console.log(quote);

8.6. Formatting Numbers#

When working with numbers, you can format them to a specific number of decimal places using the toFixed() method. The result is always returned as a string.