JavaScript Debugging Console

Console Like a Pro

The browser console is the most important debugging tool for JavaScript beginners.

If you learn how to use the console properly, you will find bugs faster and understand your code better.

How to Open the Console

In Chrome or Edge, open the console like this:

• Right-click anywhere on the page
• Click Inspect
• Click the Console tab

console.log()

The most common console method is console.log().

Use it to print values and see what your program is doing.

Examples

console.log("Hello from JavaScript!");

console.warn()

Use console.warn() to display warnings.

Warnings tell you something might be wrong, but your code can still run.

Example

console.warn("This is a warning!");

console.error()

Use console.error() to display error messages.

Errors show that something has failed.

Example

console.error("Something went wrong!");

Logging Multiple Values

You can log more than one value at once.

Example

let x = 10;

let y = 5;

console.log("x =", x, "y =", y);

Inspecting Objects

The console is very useful for inspecting objects.

Example

let user = {name: "John", age: 25};

console.log(user);

console.table()

Use console.table() to display data in a table format.

Example

let users = [

  {name: "John", age: 25},

  {name: "Anna", age: 30}

];

console.table(users);

Debugging Tip: Stop Guessing

Beginners often guess what the value is.

Professionals log the value and confirm it.

If your code is not working, do not guess.

Use console.log().

Next: Breakpoints, Watch, Scope

Logging is powerful, but sometimes you need to pause code execution.

Next page: Learn how to use breakpoints, step through code, and watch variables live.