/ How to

How to Add and Use Debug Breakpoints in Visual Studio Code Editor

As a software developer with over 10 years of experience coding in various languages and frameworks, I utilize the debugging capabilities in IDEs on a daily basis. Setting breakpoints is an essential part of debugging code and fixing bugs efficiently.

Visual Studio Code has excellent built-in debugging support, including the ability to easily add, remove and manage breakpoints. Here is a comprehensive guide on how to leverage this powerful feature.

What is a Debug Breakpoint?

A breakpoint is a marker that you set in your code editor that tells the debugger to temporarily pause execution of your program at that point. This allows you to inspect the values of variables, check the call stack, and step through your code line-by-line to understand the runtime flow and detect issues.

Key benefits of using breakpoints include:

  • Inspect program state during execution
  • Understand control flow
  • Detect unexpected variable values
  • Identify source of bugs and errors
  • Test assumptions and hypotheses

Adding Breakpoints in VS Code

Adding a breakpoint in VS Code is very simple:

  1. Open the JS file you want to debug in the editor
  2. Click on the line number in the gutter on the left side – this sets a breakpoint

Alternatively, with your cursor on a line:

  • Linux/Windows: F9
  • macOS: fn + F9

A red dot appears in the gutter marking the breakpoint.

Breakpoint Types

There are a few different types of breakpoints you can set:

  • Line breakpoint – pauses execution at the beginning of the line
  • Conditional breakpoint – pauses only when condition is met
  • Logpoint – logs a message instead of pausing

Using Debug Breakpoints

Once you’ve added breakpoints, you can start your debugging session:

  1. Open your project folder in VS Code
  2. Switch to the Debug view
  3. Select the debugging environment from the dropdown (e.g. Chrome)
  4. Press the green Play button to start debugging

As execution hits a breakpoint, code will pause and you can inspect the current state:

  • See the Call Stack and Variables panes
  • Interact with the debugger using the Debug actions pane
  • Hover over variables to see their value
  • Use the Watch pane to track values
  • Step through code line-by-line

Key Debugging Features

  • Step Over (F10) – execute next line and skip functions
  • Step Into (F11) – step into next function call
  • Step Out (Shift + F11) – run until function returns
  • Restart (Ctrl + Shift + F5) – restart debugging session

Tips for Effective Breakpoint Usage

Here are some tips for working with breakpoints:

  • Set breakpoints before areas with suspected issues
  • Use conditional breakpoints to isolate problem inputs
  • Break on thrown exceptions to catch errors
  • Monitor key variables with logpoints
  • Clean up breakpoints after fixing issues
  • Take advantage of advanced breakpoint options

Pro Tip: Set a breakpoint that logs a message instead of breaking using a logpoint. This allows you to get debugging data without pausing execution!

Summary

Debug breakpoints are invaluable when trying to diagnose issues in your code. VS Code makes setting and utilizing them easy and straightforward.

The key concepts include:

  • Breakpoints pause execution at a line
  • Allow inspection of runtime state
  • Support different types like conditional and logpoints
  • Start a debug session to hit breakpoints
  • Control flow using Step Over, Step In and Step Out
  • Use effectively to maximize productivity

With robust debugging support and feature-rich editor, VS Code can greatly accelerate your ability to fix bugs and write better code. Mastering breakpoints is a must for any developer working in VS Code.

Related Posts