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Discussion on: Why do we write JavaScript like this?

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functional_js profile image
Functional Javascript

Choosing implementation variants is straightforward if you adhere to a predefined criteria set.

I write about how to evaluate implementations on criteria here:
TLDR: Choose the fastest implementation considering equal robustness.
dev.to/functional_js/squeezing-out...

In this case, the loop is many magnitudes faster. Use the loop.

//a.
const isPalindrome_loop = str => {
  const s = str.toLowerCase();
  for (let i = 0; i < s.length / 2; ++i) {
    if (s[i] !== s[s.length - 1 - i]) {
      return false;
    }
  }
  return true;
};

//b.
const isPalindrome_spread = str => {
  const s = str.toLowerCase();
  return [...s].reverse().join("") === s;
};

//@tests
const palid = "A man, a plan, a canal: Panama—!@#$#@%$$%^&&^*()=-_+,.<>/?";

//a.
timeInLoop("isPalindrome_loop", 1e6, () => isPalindrome_loop(palid));
// isPalindrome_loop: 1e+6: 162.986ms

//b.
timeInLoop("isPalindrome_spread", 1e6, () => isPalindrome_spread(palid));
//isPalindrome_spread: 1e+6: 5.494s
Thread Thread
anders profile image
Anders Author

Very clear comparison of the actual performance of the two.

I do wonder though why declaring the actual functions as "function Name(arg) { ..." has fallen somewhat out of favor, it just seems such a more natural way to do it given how the English language works.

Then again in most other languages you'd typically see:
returnType FunctionName(args) {
or something similar to that

Thread Thread
functional_js profile image
Functional Javascript

That's a good question, here's my answer to it:

I don't understand why people still use the "function" keyword, unless you are accessing the "this" keyword, which should be never, except for legacy JavaScript.

Plus I would pick one consistent strategy and go with it, instead of intermingle, "sometimes arrow and sometimes function".

I also don't use single quotes. Everything double quotes.
Then there's none of this, "sometimes this, sometimes that" sprinkled all over the place.

I'm a minimalist, and only use a subset of the language.
Here is a list of what I don't use in JavaScript:
dev.to/functional_js/what-subset-o...

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anders profile image
Anders Author

Thanks for that response.

I agree, consistency is key. Which is why on my projects there are always a set of coding guidelines that are enforced in terms of naming, spacing, comments, all that.

I do use the "this" keyword relatively frequently however myself, specifically from within member functions of an object, to access member data or other member functions.

Thread Thread
functional_js profile image
Functional Javascript

That's because of your Object-oriented approach to programming.

I use a functional approach, so everything in that list I linked to in my last post are unnecessary.

Without those constructs, there is almost nothing left but funcs themselves, specifically, arrow funcs.

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