IMPORTANT NOTE (4/10/2020): As of today, I see Instagram has enabled DM on the Web. I don't think this add-on is longer needed, unless you want to chat on a tiny bottom-right window, instead of the whole window. Thanks to all who installed and submitted those friendly reviews!
This add-on allows you to chat on the Instagram Web app, which is not available by default although the functionality is there.
Functionality Modifies the Instagram page doing the following:
Adds new chat icon on the top-right menu
Shows/hide a chat-box once you click on the new chat icon
How it's done For a technical explanation, check this add-on's website or the "Technical Details" section.
Developer comments
Only for the direct chat URLs, this add-on makes Instagram think the user is browsing on a mobile device. This is done on a background script as follows:
Intercept chat HTTP requests (only for the ".../direct/inbox/*" URLs.
Changes the request's user-agent to mobile
A hidden "iframe" element is created for the direct chat URL along with a chat toggle on the page top-right menu. Their mobile direct chat looks pretty ugly, so this add-on also does some tweaks to improve its design. It's all done as follows:
Creates a chat icon toggle on the top-right menu
Creates a hidden iframe for the chat inbox
Tweaks on chat inbox: white background color, overlapping header, blocking "return to home" link, fixed "send message" input on bottom
A hidden "iframe" element is created for the direct chat URL along with a chat toggle on the page top-right menu. Their mobile direct chat looks pretty ugly, so this add-on also does some tweaks to improve its design. It's all done as follows: