Added String.prototype.replaceAll method

[Greeshmanth1909]

resolves #1174
Added String.prototype.replaceAll method in case a browser doesn't support it by default.
Here are the tests I performed:

• Ran npm run serve
• Ran npm run preview
• Tested with npm test
  In all the above cases I was able to browse and open zim files in both serviceWorker and JQuery modes in Chrome, Firefox (only JQuery) and Brave. I could't test the magnet link generation for older browsers.
• Tested the extension for Firefox.
• Tested the extension for Chrome in both JQuery and ServiceWorker modes.

[Jaifroid]

@Greeshmanth1909 Thank you! I'll test this on a Chrome < 85 and Firefox < 77 with the download library.

[Jaifroid]

I should get to this this weekend.

[Greeshmanth1909]

Pushed the code for a completely different issue to this pr by accident. Will fix it asap.

[Jaifroid]

Thanks very much for this PR. I tested it in Firefox Portable ESR 70.1, and unfortunately it doesn't appear to be working as intended. I get the error magnetLink.replaceAll is not a function when clicking on the "Download" link in the library. See screenshot below. Perhaps you haven't injected the function into the correct context? The library code runs in an iframe,

[Jaifroid]

You can get different versions of Firefox Portable here: https://sourceforge.net/projects/portableapps/files/Mozilla%20Firefox%2C%20Portable%20Ed./

[Greeshmanth1909]

Ill try fixing it. Thanks for the resource.

[Jaifroid]

I was thinking you might run into CORS issues attempting to inject this function into the library iframe. In fact you almost definitely will, unless there is a known way to polyfill browser functions in a way that works also in iframes with third-party content. It seems unlikely, as it would be considered a vector for attack.

Given this, the only solution -- I think -- would be to make a PR (or suggest a PR) over at kiwix-tools (https://github.com/kiwix/kiwix-tools). I'm sorry if the issue misled you here, I only realized this might be an issue after polyfilling the function in init.js appears to have failed.

[Greeshmanth1909]

I've also tried defining the polyfill in an inline script of library.html it didn't work.

[Greeshmanth1909]

Shall I close this pr? @Jaifroid

[Jaifroid]

Unfortunately, yes, it sounds like there is no solution on our end. But there is a solution on the kiwix-tools end, so I encourage you to open a ticket, and perhaps show the suggested polyfill code, upstream. Explain why it's needed -- to allow older browsers to use Kiwix Serve's download code.