Javascript - Case insensitive Array Search

Question

This code gets rid of all the duplicate variables. Is there a way to make the array search in this function case insensitive?

var x = ["AAA", "aaa", "bbb", "BBB"];

function unique(list) {
  var result = [];
  $.each(list, function(i, e) {
    if ($.inArray(e, result) == -1) result.push(e);
  });
  return result;
}

// Output should be AAA, bbb
console.log(unique(x));

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

Associated JSFiddle here

Honestly, the easiest way is to just `.toLowerCase()` on everything, so that there is a always the same case — Sterling Archer, Mar 19 '18 at 17:13
Possible duplicate of [How do I make Array.indexOf() case insensitive?](https://stackoverflow.com/questions/24718349/how-do-i-make-array-indexof-case-insensitive) — ZaidRehman, Dec 17 '18 at 15:03

Ele · Accepted Answer · 2018-03-19T17:29:19.627

You don't need jQuery.
Use the function findIndex and convert to lowerCase every element for each comparison.

var x = ["AAA", "aaa", "bbb", "BBB"];

function unique(list) {
  var result = [];
  list.forEach(function(e) {
    if (result.findIndex(function(r) {
      return r.toLowerCase() === e.toLowerCase();
    }) === -1)
    
    result.push(e);
  });
  
  return result;
}

console.log(unique(x))

.as-console-wrapper { max-height: 100% !important; top: 0; }

Using arrow functions:

var x = ["AAA", "aaa", "bbb", "BBB"];

function unique(list) {
  var result = [];
  list.forEach((e) => {
    if (result.findIndex((r) => r.toLowerCase() === e.toLowerCase()) === -1)   
    result.push(e);
  });
  
  return result;
}

console.log(unique(x))

.as-console-wrapper { max-height: 100% !important; top: 0; }

"A small group of characters, when they are converted to lowercase, cannot make a round trip. To make a round trip means to convert the characters from one locale to another locale that represents character data differently, and then to accurately retrieve the original characters from the converted characters." — Anar Sultanov, Oct 09 '18 at 07:45

score 0 · Answer 2 · answered Mar 19 '18 at 17:16

You could use a lookuptable with only lowercase entries:

function unique(arr){
  const before = new Set, result = [];

  for(const str of arr){
   const lower = str.toLowerCase();
   if(!before.has(lower)){
    before.add(lower);
    result.push(str);
   }
  }
  return result;
}

That in a oneliner:

const unique = arr => (set => arr.filter(el => (lower => !set.has(lower) && set.add(lower))(el.toLowerCase()))(new Set);

score -1 · Answer 3 · edited Mar 19 '18 at 18:11

-1

Just add .toLowerCase to everything

var x = ["AAA", "aaa", "bbb", "BBB"];

function unique(list) {
  var result = [];
  $.each(list, function(i, e) {
    if ($.inArray(e.toLowerCase(), result) == -1) result.push(e.toLowerCase());
  });
  return result;
}

alert(unique(x));

edited Mar 19 '18 at 18:11

Fraser

15,275
8
53
104

answered Mar 19 '18 at 17:20

Juan Patrono

1

kishea · Answer 4 · 2018-03-19T17:40:34.670

-1

just a little tweaking and you will be there

function unique(list) {
    var result = [];
    $.each(list, function(i, e) {
        if($.inArray(e, list)){ result.push(e)};
    });
    return result;
}

that works fine

no need to case change

edited Mar 19 '18 at 17:40

answered Mar 19 '18 at 17:33

kishea

637
1
6
17

Javascript - Case insensitive Array Search

4 Answers4