Tampermonkey, Chrome, how to change html entities back to symbols?

Question

There's a webpage that messes up html code by embedding it within another html code and when I try to replace the entities with their symbol equivalents, it just removes everything.

Here's the code I tried:

var marks = document.getElementsByTagName("body");
      for(var i = 0, l = marks.length; i < l; i++)
      {
         var mark = marks[i];
         mark.innerHTML = mark.innerHTML.replace('&lt;', '<');
         mark.innerHTML = mark.innerHTML.replace('&gt;', '>');
         mark.innerHTML = mark.innerHTML.replace('&amp;', '&');
      }

but here's what it does: https://jsfiddle.net/rkb89odm/2/

Can you tell if the problem lies in the replace call, or when you assign to innerHTML? — Josh Lee, Aug 30 '17 at 13:22

score 1 · Accepted Answer · answered Aug 30 '17 at 13:33

First, you're only replacing the first occurrence, not all occurrences.

> '&lt;html&gt;&lt;body&gt;'.replace('&lt;', '<')
< "<html&gt;&lt;body&gt;"
> '&lt;html&gt;&lt;body&gt;'.replace(/&lt;/g, '<')
< "<html&gt;<body&gt;"
> '&lt;html&gt;&lt;body&gt;'.replace(/&lt;/g, '<').replace(/&gt;/g, '>');
< "<html><body>"

See How to replace all occurrences of a string in JavaScript?

Second, I would avoid round-tripping partially valid markup through the browser, as it might not be the same when it comes back to you. Run all the replacements before putting it back in innerHTML.

let s = mark.innerHTML;
s = s.replace(/&lt;/g, '<')
s = s.replace(/&gt;/g, '>');
mark.innerHTML = s;

It worked for the most part, but after loading non-breaking spaces and + signs appear as and + and I can't replace them the same way. — Máté Burján, Aug 31 '17 at 06:38
Nevermind, had to replace the & sign separately, thank you for helping. — Máté Burján, Aug 31 '17 at 07:00

Tampermonkey, Chrome, how to change html entities back to symbols?

1 Answers1