Firefox Extension FavIconUrl is super long. Any way to shrink it?

Question

I am working on a cross-browser extension and use the "tabs API" (https://developer.chrome.com/docs/extensions/reference/tabs/) to store relevant information about each tab.

One of these fields is the tab's favIconUrl.

Problem

In Chrome & Microsoft Edge, this field is given as a URL string and is usually relatively short (a few bytes).

However in Firefox, this is given as a data:image/x-icon;base64 string and is VERY long (a couple of KB).

The problem is that I use storage.sync and this resource is sparse per item stored - so what takes up nothing in Chrome/Edge, is barely enough in Firefox for a single tab.

Example (Facebook Tab)

Chrome & Microsoft Edge:

https://static.xx.fbcdn.net/rsrc.php/yo/r/iRmz9lCMBD2.ico

Firefox:

data:image/x-icon;base64,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Ideas?

Any ideas how I can shorten this Base64 string?

Ideally, I would need some decoder that decodes base64 but keeps regular URL strings unchanged.

Answer 1

For others that might face the same issue in the future.

THIS APPROACH IS GOOD, BUT YOU RISK VIOLATING CSP DUE TO USING BLOBS... SEE VERY BOTTOM FOR BETTER SOLUTION

I ended up converting it to a blob url by modifying this answer to my needs: https://stackoverflow.com/a/16245768/4298115

function convertToShortURL(input_str, sliceSize = 512) {
  if (input_str && input_str.includes("base64")) {
    input_str = input_str.split(",")[1]; // get the base64 part
    const byteCharacters = atob(input_str);
    const byteArrays = [];

    for (let offset = 0; offset < byteCharacters.length; offset += sliceSize) {
      const slice = byteCharacters.slice(offset, offset + sliceSize);

      const byteNumbers = new Array(slice.length);
      for (let i = 0; i < slice.length; i++) {
        byteNumbers[i] = slice.charCodeAt(i);
      }

      const byteArray = new Uint8Array(byteNumbers);
      byteArrays.push(byteArray);
    }

    const blob = new Blob(byteArrays);
    return URL.createObjectURL(blob);
  } else {
    return input_str;
  }
}

Explanation

This function takes in an input string that you would get from tab.favIconUrl using the "Tabs API" and if it is a base64 string, will return a short blob url - which you can then use the same way as a url string. Otherwise, if the input is already a url string or undefined (not base64), the function simply returns it as is.

BEST APPROACH

Based on:

1. https://stackoverflow.com/a/8498629/4298115 (domain from url)
2. https://stackoverflow.com/a/3880629/4298115 (favicon from domain)

function getFavIconURL(url) {
  var matches = url.match(/^https?\:\/\/([^\/?#]+)(?:[\/?#]|$)/i);
  var domain = matches && matches[1]; 
  return "http://www.google.com/s2/favicons?domain=" + domain;
}

This function simply returns the favicon url without returning a blob file.

Simple and elegant in my opinion. Cheers!