Verify timeoutID before calling clearTimeout

[ypconstante]

Actual behaviour

When destroying a chart, Highcharts calls clearTimeout a lot of times. For some reasons, browsers are kind of slow when calling clearTimeout with a null or undefined value, which is what happens a lot of times in this clearTimeout calls. In some tests I've made, the time for the execution of clearTimeout and removeChild were the same.

Live demo with steps to reproduce

clearTimeout performance demo: https://jsperf.com/null-check-cleartimeout-vs-cleartimeout-null/3

Product version

Highcharts 6.0.7

Affected browser(s)

Chrome 64

[pawelfus]

@ypconstante - it looks like your jsperf is broken, could you update the URL?

[ypconstante]

jsperf is returning error in every page right now.