JS : arrow function or array map?

Question

Based on this code, I would like to use an arrow function, I am not really used to.. What's the best way to wrote it ?

I would like to keep the same sort order. Since "selectedHeader" is like you can guess, a column variable based on a vue js v-select.

const headers = 
  [ { text: 'City',                  value: 'city'   } 
  , { text: 'Zip code',              value: 'zip'    } 
  , { text: 'Country',               value: 'country'} 
  , { text: 'Number of Inhabitants', value: 'inhabitants' } 
  ];

const selectedHeaders = 
  [ { text: 'City',     value: 'city' } 
  , { text: 'Zip code', value: 'zip'  } 
  ];
  
let tab = [];

for (i = 0; i < headers.length; i++) {
  pos = selectedHeaders.map(function(e) {
    return e.value;
  }).indexOf(headers[i].value);
  if (pos > -1) {
    tab.push(headers[i]);
  }
}

console.log(tab);

Have you tried [testing each approach](https://stackoverflow.com/questions/111368/how-do-you-performance-test-javascript-code)? — D M, Nov 02 '21 at 14:03
It’s not clear what you’re asking. An arrow function for what? The `map` function? Faster than what? It’s unlikely a performance gain here would be meaningful. — Dave Newton, Nov 02 '21 at 14:03
You might want to declare your `i` and `pos` variables though. — pilchard, Nov 02 '21 at 14:05
The expected output is the actual tab. I do believe using for like this is not a good practice. I try to improve myself. — Zabz, Nov 02 '21 at 14:07
@Zabz They’re identical as-is. The point was that there’s little here that explicitly describes the issue or problem you’re actually facing. — Dave Newton, Nov 02 '21 at 14:11
no, the point is you don't read. I wrote it : "I would like to keep the same sort order.". Anyway, Pedro answered it. — Zabz, Nov 02 '21 at 15:03

score 1 · Accepted Answer · answered Nov 02 '21 at 14:06

If you want to use arrow functions, you can use filter

    const headers = [ { "text": "City", "value": "city" }, { "text": "Zip code", "value": "zip" },{ "text": "Country", "value": "country" },{ "text": "Number of Inhabitants", "value": "inhabitants" }];
    const selectedHeaders = [ { "text": "City", "value": "city" }, { "text": "Zip code", "value": "zip" }];
    let tab =[];
    
    const selectedValues = selectedHeaders.map(header => header.value);
    tab = headers.filter(header => selectedValues.includes(header.value));
    console.log(tab);

Thanks you, that's exactly what I was looking for. I am going to try to understand it as much as I can. — Zabz, Nov 02 '21 at 14:08

JS : arrow function or array map?

1 Answers1