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Getting the source HTML of the current page from chrome extension

javascript
script-injection
error-handling
dom-query-selector
Alex KataevbyAlex Kataev·Feb 8, 2025
⚡TLDR

To capture the page's HTML in a Chrome extension, inject a script with chrome.scripting.executeScript that grabs document.documentElement.outerHTML. Here's a concise snippet:

// Who needs treasure maps when you have JavaScript!
chrome.tabs.query({active: true, currentWindow: true}, tabs => {
  // "Going fishing" for the HTML, wish me luck
  chrome.scripting.executeScript({
    target: {tabId: tabs[0].id},
    func: () => document.documentElement.outerHTML,
  }, results => {
    console.log(results[0].result); // Jackpot! We found the HTML gold.
  });
});

Arr matey, don't forget ye manifest permissions for activeTab and scripting. This snippet logs the HTML treasure, ready for you to pillage or hoard as you see fit.

Implementing and Managing Script Injection

To prevent premature page interaction, use window.onload with chrome.scripting.executeScript. It ensures the page is fully dressed👗, and your extension isn't looking at it in its undergarments. For instant action, uncomment injectImmediately.

Handling Errors and Stop the Ship from Sinking 🚢

When injecting scripts, or dealing with messages via chrome.runtime.onMessage.addListener, be ready to plug-in error leaks. Try-catch blocks and message content validation can preserve extension integrity and provide seamless sailing.

Aiming the Cannon - Targeting HTML Elements

Sometimes, you need to aim at specific elements. Use an args parameter with a DOM query selector to hit your mark💥. If the shot misses, have a plan B to handle the absence of the target node.

Fishing Techniques for Data Extraction

For snatching smaller fish in the HTML sea, use regular expressions. Apply judiciously; too many nets in water might slow down the ship.

Navigating Rough Waters with permissions and Manifest Configuration

Make sure the manifest.json maps out permissions like "activeTab", "scripting", and "tabs". Wrongfully marked maps lead to troubled waters.

Further Expeditions Beyond HTML Capture

Data Analysis

Analyze the HTML treasure for SEO gems, content gold, or test DOM manipulations.

User Feedback Enhancement

Empower users to start the treasure hunt with a simple browser action button.

Debugging Journeys

Use the extension to explore and fix mysterious lands of web pages.

More Wisdom for the Voyage - General Best practices

Testing the Ship

Before sailing, ensure the ship withstands different weathers and performs consistently across several islands (webpages).

Uncharted Territories

Not all lands are similar. Watch out for hidden iframes, dynamic scripts, and asynchronous data loads.

Keeping the Crew Happy - User Experience (UX)

Design a ship (extension) that's easy to sail with clear maps (notifications), voyage indicators (progress), and warning signals (error messages).

explain-codes / Javascript / Getting the source HTML of the current page from chrome extension
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Implementing and Managing Script InjectionHandling Errors and Stop the Ship from Sinking 🚢Aiming the Cannon - Targeting HTML ElementsFishing Techniques for Data ExtractionNavigating Rough Waters with permissions and Manifest ConfigurationFurther Expeditions Beyond HTML CaptureMore Wisdom for the Voyage - General Best practices
Linked

Access variables and functions defined in page context from an extension

How to defer inline Javascript?

How can I inspect disappearing element in a browser?

How do I preserve line breaks when getting text from a textarea?

Is there a HTML opposite to ?

Violation Long running JavaScript task took xx ms

Confirmation before closing of tab/browser