Calling JSON.stringify on arguments fails

[ndhoule]

Running latest PhantomJS, 1.9.2, on both OS X 10.9 and Ubuntu 12.04. Installed phantomjs both via brew and npm, no difference in behavior.

Here's the code I'm trying to use:

var memoize = function(func) {
  var memos = {};
  return function() {
    var serialization = JSON.stringify(arguments);
    return memos[serialization] = memos[serialization] || func.apply(this, arguments);
  };
};

(Sidenote: Declaring this function at the PhantomJS console errored, told me that it was a cyclic structure. Same problem persisted when not at the console, though.)

And my test cases:

var fib = function(n) {
  if (n < 2) { return n; }
  return fib(n - 1) + fib(n - 2);
};
var fastFib = memoize(fib);

expect(fib(10)).to.equal(55);      // Passes
expect(fastFib(10)).to.equal(55);  // Passes
expect(fastFib(7)).to.equal(13);   // Fails, returns 55

I narrowed this down by throwing a console.log(JSON.stringify(arguments)) just below var serialization, above. It logs {}. I also experienced the same behavior when trying to console.log(arguments), though console.log(arguments[0]); worked fine.

[JamesMGreene]

This is due to the old version of WebKit that Phantom 1.x runs on. Phantom 2.0 should eliminate this problem.

Until then, here's a workaround that should do the trick:

var args = Array.prototype.slice.call(arguments, 0);
console.log(JSON.stringify(args));

[ndhoule]

Gotcha, thanks a lot!

[ariya]

Fixed in Qt5-based master branch.