How to debug JavaScript code?

How do I debug JavaScript in HTML?

Start debugging

  1. Set the breakpoints in the JavaScript code, as required.
  2. Open the HTML file that references the JavaScript to debug or select the HTML file in the Project tool window.
  3. From the context menu of the editor or the selection, choose Debug <HTML_file_name>.

How do you debug a code?

7 Steps to Debug Efficiently and Effectively

  1. 1) Always Reproduce the Bug Before You Start Changing Code.
  2. 2) Understand Stack Traces.
  3. 3) Write a Test Case that Reproduces the Bug.
  4. 4) Know Your Error Codes.
  5. 5) Google! Bing! Duck! Duck! Go!
  6. 6) Pair Program Your Way Out of It.
  7. 7) Celebrate Your Fix.

How do I debug JavaScript in chrome?

Press the F12 function key in the Chrome browser to launch the JavaScript debugger and then click “Scripts”. Choose the JavaScript file on top and place the breakpoint to the debugger for the JavaScript code. Ctrl + Shift + J opens Developer Tools.

How do you step through JavaScript?

2 Answers

  1. Hit the F12 key.
  2. Select the Scripts , or Sources , tab in the developer tools.
  3. Click the little folder icon in the top level.
  4. Select your JavaScript file.
  5. Add a breakpoint by clicking on the line number on the left (adds a little blue marker)
  6. Execute your JavaScript.

How do I trace HTML code?

4 Answers

  1. Click on the Wrench symbol on the top right of the Chrome screen, select Tools, and select Developer Tools.
  2. Click on the Scripts tab on the bottom pane of the Chrome Screen.
  3. Click on Folders on the top left corner of the bottom pane of the Chrome Screen.
  4. Click on the script that you want to debug.
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How do you debug HTML code?

Click any element with right mouse button > inspect. Use Ctrl+Shift+I (or Cmd+Opt+I on Mac) to open the DevTools and pick the Elements tab.

How do I debug?

Select a device to debug your app on. Set breakpoints in your Java, Kotlin, and C/C++ code. Examine variables and evaluate expressions at runtime.

Attach the debugger to a running app

  1. Click Attach debugger to Android process .
  2. In the Choose Process dialog, select the process you want to attach the debugger to. …
  3. Click OK.

Why is debugging so difficult?

The original justification for “setter” methods was the realization that allowing anybody to modify instance variables made them indistinguishable from global variables – hence making debugging much more difficult. Therefore, if one prevented direct access to the instance variable, it would fix that problem.

How can I improve my code debugging skills?

5 Ways to Improve Your Debugging Skills

  1. Understand the internals of your OS.
  2. Learn to use more advanced debugging tools.
  3. Expose yourself to a greater variety of code.
  4. Explain your code out loud.
  5. Learn to identify code smell.

How do I debug my browser?

Chrome

  1. Step 1: Open your application in the Chrome web browser.
  2. Step 2: Open developer console by inspecting your web page and select source tab or Go to View → Developer → View Source.
  3. Step 3: Set the breakpoint on your source code something similar to what we did in Mozilla browser.

How do I debug HTML in Chrome?

Debugging Your Website with Chrome Developer Tools

  1. In your Chrome browser, open the site you want to debug.
  2. Right click over an element you want to debug. In this example, we’re analyzing a yellow button.
  3. Click “Inspect”.
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How do I get the JavaScript code from a website?

Go to the outer edge of a site (e.g. far left), then right-click and click on “View Page Source” (or the option that’s similarly named). That will bring up all the HTML code, along with links to CSS files, Javascript, images, etc. You can now read through it and see what that page is created with.

Where can I test JavaScript code?

Let us have a quick look at some of the most popular ways to test JavaScript code in a browser.

  1. JSFiddle. Whether you are working with JavaScript or frameworks like React and Vue, JSFiddle is the tool for you. …
  2. Cross Browser Testing Tools. …
  3. Karma + Jasmine + Google Chrome. …
  4. CodePen. …
  5. JSBin. …
  6. Liveweave.

How do you debug a backend code?

Debugging Back End (Node. js)

  1. Launch your project in VS Code.
  2. Navigate to Console tab.
  3. Enter or paste npm start –inspect command and press Enter.
  4. Launch Chrome and enter or paste “about:inspect”. This will redirect you to the Devices page of DevTools.
  5. Click Open dedicated DevTools for Node hyperlink.

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