It compiles the Java source, not the Java bytecode, but even if it did.... Take your malloc example, you can compile a C program that uses malloc to JS, you ju

It compiles the Java source, not the Java bytecode, but even if it did.... Take your malloc example, you can compile a C program that uses malloc to JS, you just have write a malloc in JS that will behave the way you expect it to. C gets compiled to assembly, assembly to machine code. Their compiler just takes Java source and emits JS source instead of JVM bytecode.