In ts.performance.now, bind window.performance.now

[Nathan Shively-Sanders (sandersn)]

Fixes#9954

Using an arrow function. Previously, it was set directly to window.performance.now, which fails when used in Chrome.

[Nathan Shively-Sanders (sandersn)]

Incidentally, I ripped off Date.now in both Chrome and Node and it works fine that way.

[Wesley Wigham (weswigham)]

👍 It's always a little disappointing how inconsistent the web is with what you can rip off its hosting object and what you cannot.

[Nathan Shively-Sanders (sandersn)]

And neither Date nor performance document it, in the documentation I found at least.

[Wesley Wigham (weswigham)]

Nathan Shively-Sanders (@sandersn) That was why I thought it was okay to rip both off. 😞

[Nathan Shively-Sanders (sandersn)]

One of the Mac builds timed out. I think it's OK to merge anyway.

[Wesley Wigham (weswigham)]

Nathan Shively-Sanders (@sandersn) This has been happening every few builds - I actually restarted a build last night that had been running for over an hour (I just assumed travis had hung). I don't know if it's a random pathological perf problem in TS that's only exposed on mac, or an issue with the travis infrastructure.

[mihailik]

FYI: compared () => performance.now() with performance.now.bind(performance), the arrow function is faster on my Chrome, faster in FireFox — but slower on IE11.

Don't have an Edge to try.

Here's the code below to run in DevTools console:

varrunAndAgain=function(){setTimeout(function(){runMillion();runAndAgain();},1);};runAndAgain();functionrunMillion(){varnow_arrow=function(){returnperformance.now();};varnow_bind=performance.now.bind(performance);varstart=newDate(),tmp=0;for(vari=0;i<1000000;i++){tmp=now_arrow();}vararrow_time=newDate()-start;varstart=newDate(),tmp=0;for(vari=0;i<1000000;i++){tmp=now_bind();}varbind_time=newDate()-start;console.log('arrow '+arrow_time+'\tbind '+bind_time+'\t ratio '+(((10000*arrow_time/bind_time)|0)/100)+'%');}

[Nathan Shively-Sanders (sandersn)]

Does anybody use IE11 to debug TypeScript? Faster in Chrome is better in my book.

[Wesley Wigham (weswigham)]

AFAIK, most of the team doesn't use IE, so the faster in chrome/FF option does seem better.

[mihailik]

I totally agree, Chrome is a better target -- and the difference is small enough anyway. Only wanted to give more context 👍