How to Set a Javascript Breakpoint from Code in Chrome?

As a JavaScript developer, you may often find yourself in situations where you need to debug your code. One of the most effective ways to debug JavaScript is by setting breakpoints. Breakpoints allow you to pause the execution of your code at a specific line, giving you the opportunity to inspect variables, step through your code, and identify any issues.

While Chrome’s DevTools provide a user-friendly interface to set breakpoints, there may be times when you want to set a breakpoint directly from your code. In this blog post, we will explore different ways to set a JavaScript breakpoint from code in Chrome.

Method 1: Using the debugger Statement

The simplest way to set a breakpoint from your code is by using the debugger statement. When the browser encounters this statement, it will pause the execution and open the DevTools at that point.

function myFunction() {
  // Some code...
  debugger; // Set breakpoint here
  // Some more code...
}

myFunction();

When you run the above code and open the DevTools, you will notice that the execution paused at the line with the debugger statement. You can now inspect variables, step through the code, and analyze the state of your application.

Method 2: Using the Console

If you prefer not to modify your code, you can also set a breakpoint directly from the console. Simply navigate to the Sources tab in the DevTools, find the JavaScript file you want to debug, and click on the line number where you want to set the breakpoint. This will insert a blue marker indicating the breakpoint.

Once the breakpoint is set, you can trigger the execution of your code, and it will pause at the specified line. You can then use the DevTools to analyze the state of your application and debug any issues.

Method 3: Using the DevTools API

If you want to programmatically set breakpoints in Chrome, you can make use of the DevTools API. This allows you to interact with the DevTools from your code and perform various debugging tasks.

chrome.devtools.inspectedWindow.eval("debugger;");

The above code snippet demonstrates how to set a breakpoint programmatically using the DevTools API. It uses the eval method to execute the debugger statement within the context of the inspected window.

By utilizing the DevTools API, you can automate the process of setting breakpoints and create more advanced debugging workflows.

Setting breakpoints from code in Chrome can greatly enhance your debugging experience. Whether you choose to use the debugger statement, the console, or the DevTools API, having the ability to pause your code at specific points allows you to gain valuable insights into your application’s behavior.

Happy debugging!