Firefox’s version 38 integrates playback mode as we've already seen on iOS for a long time. Accessible from a small icon on the right in the address bar, it only displays the text content of a web page in a so-called playback mode. If you find this new option unnecessary and bulky, read this article!
To do this, open Firefox, and enter into the URL bar about:config and do Entry.
Click on I'll be careful, I promise!
Search for the following line:
Change the value of the option to false double-clicking on it.
The changes are instantaneous.
The icon has disappeared from the URL bar. To reactivate it, turn the option to true.