How can I short this function in Javascript (ES6)

Question

i have this functions:

'use strict';
const toSuit1 = (card) => card.charAt(card.length - 1); //only color

function isFlush(hand) {
  const suits = hand.map(toSuit1).sort();
  let result;
  if (suits[0] === suits[4]) {
    result = 'true';
  } else {
    result = 'false';
  }
  return result;
}

console.log(isFlush(['7H', '2H', 'QH', '10H', '5H'])); // true
console.log(isFlush(['7H', '2H', 'QX', '10H', '5H'])); // false

Now I want to shorten this. But it doesn't work. But I still have problems with understanding and shortening. Can I make the const suit as an extra function?

'use strict';
const toSuit1 = (card) => card.charAt(card.length - 1); //only color
const suits = (hand) => hand.map(toSuit1).sort();
const isFlush = (suits) => suits[0] === suits[4] ? 'true' : 'false';

console.log(isFlush(['7H', '2H', 'QH', '10H', '5H'])); // true
console.log(isFlush(['7H', '2H', 'QX', '10H', '5H'])); // false

You never call the suits function. Furthermore, you shadow it with the parameter of isFlush, so you cannot call it. — VLAZ
– VLAZ, Commented Mar 24, 2021 at 10:24
Sometimes default sort doesn't work as expected.bugs.chromium.org/p/v8/issues/detail?id=90 You can use your own sort algoritm. sort((a,b)=> // compare ) — Murat Çimen
– Murat Çimen, Commented Mar 24, 2021 at 10:26
I think you do not need suits; you can check whether the hand is a flush by doing: const isFlush = (hand) => !hand.some(card => toSuit1(card) !== toSuit1(hand[0])). In other words you check whether there is at least one card whose color is different from the one of the first card — secan
– secan, Commented Mar 24, 2021 at 10:54
btw, why do you want a string as result? keeping it boolean would serve better later without convering a string back to boolean. — Nina Scholz
– Nina Scholz, Commented Mar 24, 2021 at 12:03
@Nina do you mean that? const isFlush = (suits) => { suits = sortSuits(suits); return suits[0] === suits[4]; } — C3PO
– C3PO, Commented Mar 24, 2021 at 13:54

ADyson · Accepted Answer · 2021-03-24 10:35:20Z

2

It's fine to separate the sorting into its own function if you want. But you need to give the suits sorting function a different name, otherwise it isn't accessible from within isFlush, as there's already a local suits variable in there. And also you need to actually call the function in order to sort the data.

Try this:

'use strict';
const toSuit1 = (card) => card.charAt(card.length - 1); //only color
const sortSuits = (hand) => hand.map(toSuit1).sort();
const isFlush = (suits) => { 
  suits = sortSuits(suits); 
  return suits[0] === suits[4] ? 'true' : 'false'; 
}

console.log(isFlush(['7H', '2H', 'QH', '10H', '5H'])); // true
console.log(isFlush(['7H', '2H', 'QX', '10H', '5H'])); // false

However since your stated goal is "shortening" the code, it's debatable whether this is really the shortest version. If the sorting function doesn't need to be a separate function (in order to make it re-usable, for example), then you can save a line of code by re-integrating it back into the isFlush function, and just using the shortened ternary syntax instead of the if in the original:

'use strict';
const toSuit1 = (card) => card.charAt(card.length - 1); //only color
const isFlush = (suits) => { 
  suits = suits.map(toSuit1).sort(); 
  return suits[0] === suits[4] ? 'true' : 'false'; 
}

console.log(isFlush(['7H', '2H', 'QH', '10H', '5H'])); // true
console.log(isFlush(['7H', '2H', 'QX', '10H', '5H'])); // false

And we could take that one step further, if the toSuit1 function also isn't re-used, then again it can be simply integrated into the sorting process directly:

'use strict';
const isFlush = (suits) => { 
  suits = suits.map((card) => card.charAt(card.length - 1)).sort(); 
  return suits[0] === suits[4] ? 'true' : 'false'; 
}

console.log(isFlush(['7H', '2H', 'QH', '10H', '5H'])); // true
console.log(isFlush(['7H', '2H', 'QX', '10H', '5H'])); // false

As you can see from this example though, "shortening" the code can come at the cost of re-usability, and readability, and the ability to independently test different aspects of the functionality. I would question whether "shorter code" should really be a target in itself. You need to strike an appropriate balance between verbosity the other factors I mentioned, rather than having a simplistic plan to make everything shorter.

edited Mar 24, 2021 at 10:35

answered Mar 24, 2021 at 10:27

ADyson

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2 Comments

VLAZ Over a year ago

Just for fun, I shortened it to this. Would definitely not recommend writing such code, though. Making the code readable and reusable is much more important.

ADyson Over a year ago

@VLAZ absolutely agreed. Cool version btw, but I certainly wouldn't want to be the one testing it :-).

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