Discussion on: Solving Puzzles With High-Performance JavaScript

[Thibault ROHMER]

Great post!

For the second problem, i'm wondering if "caching" the char helps:

        var c = s[front];
        if (c !== 'a' &&
            c !== 'e' &&
            c !== 'i' &&
            c !== 'o' &&
            c !== 'u' &&
            c !== 'A' &&
            c !== 'E' &&
            c !== 'I' &&
            c !== 'O' &&
            c !== 'U') {
            front++;
            continue;
        }

Rather than accessing s[front] for each test, especially when the char is not a vowel.
Maybe the js engine already optimizes your code 🤔.
Sure there's an extra affectation which cost time, but s[front] has to be "computed" each time. It's a direct memory access, but first an addition is in order to add front index to the s array adress, right ?
So what is faster:

• 10 additions + 10 read
• or 1 write + 10 read ?

Difference is probably marginal, but wondering how much the assembler code changes. And if the jit optimizes that.

[Andrew Healey]

Interesting proposal. I ran it ten times on LeetCode and didn't get a faster answer (not that that means anything!).

I ran both functions one million times on a 445-char lorem ipsum text in Chrome latest. It seems that caching the variable is marginally faster 😊