_.throttle bugs in v1.5.0

[jdalton]

In addressing #926, via 081c9fa when you're throttling with the leading options as false it checks for !previous but once you've executed the throttled function and the wait has expired and you call the throttled function again it won't behave properly, incorrectly executing on the leading edge of wait.

[jdalton]

Again, a little time between patching and bumping would do a lot of good.

[jashkenas]

Seems to be working to me, or perhaps you've mis-worded your bug report. Feel free to add a failing test case if you have one.

[jdalton]

You should tweak your test.

Because previous is set from the previous successful round of throttling it will ignore options.leading when false and incorrectly execute func on the next leading edge of wait.

It results in something like:

var func = function() { console.log('hiya'); };
var throttled = _.throttle(func, 100, { 'leading': false, 'trailing': true });

throttled();
_.delay(throttled, 200);
_.delay(function() { console.log(250) }, 250);

It will incorrectly report:

hiya
hiya
250

Instead of

hiya
250
hiya

[jdalton]

I don't think patch 7c658b2 is right either. As now it mods previous on every execution causing it to muck with the way remaining is calculated. Hold up for a sample failing case.

[jdalton]

Ok, so now

var func = function() { console.log('hi') };
var throttled = _.throttle(func, 100, { leading: false, trailing: true });

var start = new Date;
while (new Date - start < 650) throttled();

will incorrectly only log 1 hi instead of 7 (6 in the loop, and 1 trailing after)

[jdalton]

I think that got it (and without adding an additional flag, \o/)