How to edit Javascript using Chrome Developer Tools

Chrome DevTools (also known as Chrome Developer Tools) is a powerful suite of tools built into the Google Chrome browser, used for editing, debugging, and monitoring JavaScript code. Next, I will briefly introduce how to use Chrome DevTools to edit JavaScript, and provide a practical example to illustrate the process.

Step 1: Open Chrome DevTools

First, open the Chrome browser and then access the developer tools using one of the following methods:

• Right-click on a page element and select 'Inspect'.
• Use the shortcut Ctrl+Shift+I (Windows) or Cmd+Opt+I (Mac).
• Through the Chrome menu, select 'More Tools' and then 'Developer Tools'.

Step 2: Navigate to the 'Sources' Tab

In the developer tools, switch to the 'Sources' tab. This panel lists all loaded resources, including JavaScript files. Locate your JavaScript file in the left-side file resource tree.

Step 3: Edit and Save Changes

In the 'Sources' panel, double-click to open a JavaScript file, then directly modify the source code in the editor. For example, you can alter function logic or add new code lines.

After editing, right-click in the editor area and select 'Save', or press Ctrl+S (Windows) or Cmd+S (Mac) to save the changes. This will temporarily save your modifications within the browser session. Note that these changes do not affect the original server files; they are temporary. To permanently save changes, you must update your codebase and redeploy.

Example

Suppose you are debugging a webpage with a button that displays the current date and time when clicked. The JavaScript code might appear as follows:

javascript
document.getElementById('showDateButton').addEventListener('click', function() {
    document.getElementById('dateDisplay').innerText = new Date().toLocaleString();
});

You find the date and time format does not meet user requirements and wish to adjust it. In the 'Sources' panel, locate this code and modify it to:

javascript
document.getElementById('showDateButton').addEventListener('click', function() {
    document.getElementById('dateDisplay').innerText = new Date().toLocaleDateString();
});

After this change, clicking the button will only display the date portion.

Conclusion

By utilizing the 'Sources' panel in Chrome DevTools, developers can directly edit and debug JavaScript code within the browser, which is highly beneficial for rapid testing and troubleshooting. This is why Chrome DevTools has become an essential tool for front-end developers and testers.