nw. nw. - 2 months ago 11
Javascript Question

Are JavaScript arrays actually linked lists?

I'm new to Javascript, and notice that you don't need to specify an array's size and often see people dynamically creating arrays one element at time. This would be a huge performance problem in other languages as you would constantly need to reallocate memory for the array as it increases in size.

Is this not a problem in JavaScript? If so, then is there a list structure available?

Answer

It most likely depends on what JavaScript engine you use.

Internet Explorer uses a mix of sparse arrays and dense arrays to make that work. Some of the more gory details are explained here: http://blogs.msdn.com/b/jscript/archive/2008/04/08/performance-optimization-of-arrays-part-ii.aspx.