isArray not used in UrlTemplateImageryProvider

[fredj]

Array.isArray is used instead of the isArray module.

[fredj]

Array.isArray is also used in WebMapTileServiceImageryProvider

[fredj]

The native Array.isArray function is widely supported, would you consider dropping isArrayand always use the native function?

[mramato]

The main reason we still have the isArray helper is to allow Cesium to still be included on sites that need to support older browsers (mainly IE8). Obviously Cesium won't work on these browsers, but trying to use a method like isArray would cause JS parsing itself to fail in certain cases, breaking the entire page. This would make it impossible for apps built with Cesium to gracefully degrade on old browsers.

We could only use the isArray helper function is global initialization code and Array.isArray everywhere else, but it's just easier to always use the helper function instead.

That all being said, we can certainly change our policy at some point in the future, but making Cesium fundamentally incompatible with IE8 is something that would need to be discussed with the community first.

[fredj]

@mramato thanks for the answer; I will change UrlTemplateImageryProvider and WebMapTileServiceImageryProvider to use isArray instead of Array.isArray