Skip to main content

JavaScript Semicolons (Live Playground)

In JavaScript, semicolons(;) are used to separate statements and indicate the end of a statement. While JavaScript has automatic semicolon insertion (ASI) that inserts semicolons when they are omitted, it's considered good practice to include semicolons explicitly to avoid potential issues and improve code readability. In this tutorial, we'll explore the use of semicolons in JavaScript and learn how to use them correctly.

Semicolons in Statements​

In JavaScript, each statement should generally end with a semicolon. Including semicolons helps indicate the end of a statement and prevents potential issues related to automatic semicolon insertion.

Example:

let x = 5;
let y = 10;
let sum = x + y;
console.log(sum); // Output: 15

In the example above, each statement ends with a semicolon, making the code clear and easy to read.

Live Playground, Try it Yourself

Semicolons and Automatic Semicolon Insertion (ASI)​

JavaScript's automatic semicolon insertion (ASI) mechanism can insert semicolons when they are omitted. However, relying on ASI can lead to unexpected behavior and issues in your code.

Example:

// prettier-ignore
let a = 5
// prettier-ignore
let b = 10
// prettier-ignore
let product = a * b
// prettier-ignore
console.log(product) // Output: 50

Although the example above works correctly, it's not recommended to rely on ASI. Including semicolons explicitly is a better practice.

Live Playground, Try it Yourself

Semicolons in For Loops and Function Expressions​

Semicolons are also used within for loop statements and after function expressions.

Example:

// For loop
for (let i = 0; i < 5; i++) {
  console.log(i);
}

// Function expression
let greet = function (name) {
  console.log('Hello, ' + name + '!');
};

In the example above, semicolons are used within the for loop statement and after the function expression.

Live Playground, Try it Yourself

Conclusion​

Semicolons play an essential role in JavaScript code, helping to separate statements and improve code readability. Although JavaScript has automatic semicolon insertion, it's considered good practice to include semicolons explicitly in your code to avoid potential issues.