You can get snapshots in JS just by structuring the code in a certain way (ala asm.js). You can get the same performance benefits by having a more limited subs

You can get snapshots in JS just by structuring the code in a certain way (ala asm.js). You can get the same performance benefits by having a more limited subset (like Dart, no eval or dynamic code loading). The real story is that Google wanted to go it alone rather than improve JS, and that's why there's Dart.