At LearnToMod, our recommendation for learning JavaScript is to divide the learning process into two stages:
1) Learn semantics, then
2) Learn syntax
We believe the first to be the hardest part. The semantics of the JavaScript language are notoriously tricky. And the domain of Minecraft modding tricky too. But this is where the LTM badges, contests, and unguided creative exploration help a lot.
When a student has a solid understanding of the semantics of coding and the semantics of the modding domain (i.e. has written some cool code with Blockly), that's a signal that he/she could transition to learning the syntax of JavaScript. (Note: we're developing some badges to help with that transition.)
We believe that if enough time has been spent on stage #1, then stage #2 is easy. Students who struggle in stage #2 are the ones who rushed through stage #1.
Eventually, we will create more javascript tutorials, though here are some JavaScript tutorials you can complete right now! And of course you can always practice coding JavaScript in the freeplay modding area.