Block Pop-ups with JavaScript

G5 Cyber Security

1 week ago

TL;DR

This guide shows you how to block pop-up windows using JavaScript code. We’ll cover a simple method that prevents most common pop-up attempts by overriding the window.open() function.

Blocking Pop-ups with JavaScript

Understand the Problem: Websites often use window.open() to create new browser windows (pop-ups). We’ll intercept this call to stop them.
Create a JavaScript Function: Write a function that will replace the default window.open() with one that does nothing or displays a message.
```
function blockPopups(url, windowName, features) {
  alert('Pop-up blocked!'); // Or any other action you prefer
  return false;
}
```
Override the window.open() Function: Assign your function to the global window.open() property.
```
window.open = blockPopups;
```

Add the Code to Your Page: Include this JavaScript code in a <script> tag within the <head> section of your HTML document.

<head>
  <script>
    function blockPopups(url, windowName, features) {
      alert('Pop-up blocked!');
      return false;
    }
    window.open = blockPopups;
  </script>
</head>

Test the Code: Open a website that normally displays pop-ups and verify that they are blocked.
Considerations & Limitations:
- This method doesn’t block all types of pop-ups. Some advanced techniques might bypass this simple override.
- Users can disable JavaScript in their browser, which will prevent this code from running.
- Some legitimate websites use pop-ups for important functions (e.g., printing). Blocking all pop-ups may break these features.

Alternative: More Robust Pop-up Blocking

For more reliable pop-up blocking, consider using a dedicated browser extension or a content security policy (CSP).