Can Javascript get a function as text?

问题:

Can Javascript get a function as text? I'm thinking like the inverse of eval().

function derp() { a(); b(); c(); }

alert(derp.asString());

The result would be something like "a(); b(); c();"

Does it exist?

回答1:

Updated to include caveats in the comments below from CMS, Tim Down, MooGoo:

The closest thing available to what you're after is calling .toString() on a function to get the full function text, like this:

function derp() { a(); b(); c(); }
alert(derp.toString()); //"function derp() { a(); b(); c(); }"

You can give it a try here, some caveats to be aware of though:

• The .toString() on function is implementation-dependent (Spec here section 15.3.4.2)
  • From the spec: An implementation-dependent representation of the function is returned. This representation has the syntax of a FunctionDeclaration. Note in particular that the use and placement of white space, line terminators, and semicolons within the representation string is implementation-dependent.
  • Noted differences in Opera Mobile, early Safari, neither displaying source like my example above.
• Firefox returns a compiled function, after optimization, for example:
  • (function() { x=5; 1+2+3; }).toString() == function() { x=5; }

回答2:

function derp() { a(); b(); c(); }

alert(derp.toString());