I'm trying to write my first firefox addon at the moment. The goal is quite simple: I'm trying to find every occurrence of a specific username on a website and replace them with a String. I can search for those occurrences manually, since theres not a huge quantity. This worked for one of the occurrences in the HTML of the website, an element which has an ID and gets displayed in a header on every instance of the website:
<a href="/user/MyUserName" id="user-profile-name" class="head-link">MyUserName</a>
This is how I replaced the username with with the String:
document.getElementById("user-profile-name").innerHTML = "The String";
I tried this and many other methods for the other occurrences, which don't have any id's, they're mainly classes:
<a href="/user/MyUsername" class="user um1">MyUserName</a>
If I try to change them with the same method, it works the first time I load the addon, but they just change back to the username when I visit a new page (with the same classes used on occurrences of the username (user um1)) or reload the page.
var list = document.getElementsByClassName("um1");
for (i=0; i<list.length; i++) {
list[i].innerHTML = "The String";
}
How can I make these changes persistent? The change should only be visual, the addons purpose is to hide a username.