Subj : Re: Compacting JS source via ParseTree or Decompile
To   : Dan Libby
From : Brendan Eich
Date : Sat Jun 05 2004 05:39 pm

Dan Libby wrote:

> When I first saw the API docs I was delighted to see 
> JS_DecompileScript(). But on further reading it looks like that won't 
> print the functions, and I have to somehow already have a list of 
> JSFunction...?

No, a script's function declarations will be properly decompiled. 
Here's a js shell example:

js> void(s = Script("function f() {\n" +
"  return 42;\n" +
"}\n" +
"function g(x, y) {\n" +
"  return x * y;\n" +
"}\n" +
"print('hi!');\n"))
js> s

function f() {
     return 42;
}


function g(x, y) {
     return x * y;
}

print("hi!");

js> uneval(s)
(new Script('\nfunction f() {\n    return 42;\n}\n\n\nfunction g(x, y) 
{\n    return x * y;\n}\n\nprint("hi!");\n'))

Note that uneval on a Script object calls toSource, which compresses 
unprettily; whereas the shell calls toString, which pretty-prints.

> Further, I'm not clear if comments/whitespace are 
> preserved in any fashion in the ByteCode.  I would imagine not, which is 
> good.

No comment or whitespace is preserved, but extra parentheses are.

> I saw a post from Brendan with a sketch for using js_ParseTokenStream(). 
>  [1]   This seems like it is probably the best option as it gives me 
> more control over the output, but does this also do syntax checking?

Yes, as the Parse in the function name implies.

/be

.