I just installed Unity 5.3, I opened one of my projects, and I wanted to edit something in one of the JavaScripts of the project, and I noticed that MonoDevelop no longer gives Autocomplete options for js, only for C#…
Is this intentional? Is it a bug? Is there any way to fix this?
Hi guys,
I had this problem as well until i found a solution (that works for me) at this older post: Mono Develop lost autocompletion and refactoring - Questions & Answers - Unity Discussions
Here’s what Oliver-Bogdan said in his answer:
What went well for me was to go to Unity > Edit > Preferences > External Tools > External Script Editor and modifiy from “MonoDevelop(built in)” to [Browse] and manually target MonoDevelop inside the Unity installation folder. For me this was “C:\Program Files (x86)\Unity\MonoDevelop\bin\MonoDevelop.exe”
Also, I figured out that you have to check the option “Add .unityproj’s to .snl” below “External Script Editor” 
After these steps, I’m using again an older version of MonoDevelop (4.0.1) with autocompletion 
I hope this can be helpful…
I’ll be answering my own question here.
So it’s true. the Built-In Monodevelop of Unity 5.3 does not have autocomplete for js. I guess they are gradually removing js support from upcoming versions of Unity, which is kinda stupid IMHO, but what can I do…
Here is a solution for the autocomplete: Install Unity 5.3 in a new folder. Don’t override Unity 5.2. After 5.3 is installed go to the installation folder and delete the MonoDevelop folder. Now copy the MonoDevelop folder from Unity 5.2 into the Unity 5.3 installation folder, and there you have it. Now if you open any js or C# from inside Unity it will be opened in the previous version of MonoDevelop and autocomplete will work for both.
In the meantime, I guess all us js scripters need to start learning the disgusting mess that is C#…
me too, auto complete helped me learn a lot… its pretty nonexpendable in my book 
use this " UnityDevelop 4.0 - UnityScript editor based on Flash Develop " Build 2259. First public build.
This still doesn’t work. I have gone through all these steps as well as those in the linked answers