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A comment on Why You Should Always Use === and Other Bad Practices. Parent comment

Re:Why You Should Always Use === and Other Bad Practices by inglor on Sunday February 09, 2014 @07:09PM (#7208168)
You're not giving the JIT a chance to warm up at all. Also, you're degrading into 'slow mode' because your array has different types. Basically, it looks like you're doing a lot of bad things to the JIT on purpose :P

Both the different types and the delete (array with holes) are _very_ harmful for performance in v8.

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Re:Why You Should Always Use === and Other Bad Practices by goldenkey on Monday February 10, 2014 @02:19AM (#7209612)
The arrays with holes are called Sparse Arrays, I googled for 'sparse array v8 performance' and didn't find much, but I've previously seen a Google Presentation on a slide-sharing site that did mention how poor sparse arrays perform when compared to normal contiguous arrays.
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