Well you are doing an array.join on 2000 elements in the 2nd example and only 20 in the first. The fact that they are undefined and therefore add up to very little output doesn't change the fact it has to process it with the join. It's your innerHTML that is taking the time now...
I guess if you are saying that you have to account for empty elements in a bigger array, then I get that - over-allocating an array would certainly cause problems as everything will have to deal with the empty space when running across the whole array. The point I'm making is that it's more performant for allocation than pushing on-demand, individual item lookup performance remains optimal, but I agree that whole comprehensions are slower if the empty space is meaningless.
As you scroll down the comments, you will see the same discussion that went through. Looks like, chrome team has recently has optimized on holey arrays. Firefox gives different results even with the link that you have provided.
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Well you are doing an array.join on 2000 elements in the 2nd example and only 20 in the first. The fact that they are
undefinedand therefore add up to very little output doesn't change the fact it has to process it with the join. It's your innerHTML that is taking the time now...Remove that inconsistency (and make it so there's enough data to really compare) jsperf.com/assign-vs-push-d2/1
I guess if you are saying that you have to account for empty elements in a bigger array, then I get that - over-allocating an array would certainly cause problems as everything will have to deal with the empty space when running across the whole array. The point I'm making is that it's more performant for allocation than pushing on-demand, individual item lookup performance remains optimal, but I agree that whole comprehensions are slower if the empty space is meaningless.
Please refer,
dev.to/svaani/comment/12443
As you scroll down the comments, you will see the same discussion that went through. Looks like, chrome team has recently has optimized on holey arrays. Firefox gives different results even with the link that you have provided.