search an array for duplicates, javascript

Question

Okay I'm trying to search an array and find the duplicates and return the number of times each of the duplicates occurs. This is what I have so far, I need to pass in two arguments first the array being searched and then a specific term within that array:

countMatchingElements = function(arr, searchTerm){
var count = 0;
for(i = 0; i <= arr.length; i++){
count++;
}
return count;
};

Array I want to search:

var arrayToSearch = ['apple','orange','pear','orange','orange','pear'];

score 1 · Answer 1 · answered Mar 01 '16 at 22:43

1

var arrayToSearch = ['apple', 'orange', 'pear', 'orange', 'orange', 'pear'];

var counter = {};

arrayToSearch.forEach(function(e) {
    if (!counter[e]) {
        counter[e] = 1;
    } else {
        counter[e] += 1
    }
});

console.log(counter); //{ apple: 1, orange: 3, pear: 2 }

answered Mar 01 '16 at 22:43

isvforall

8,768
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1

This will work for the original problem. Just be aware that it won't work if you're looking for duplicate objects/arrays. – Mike Cluck Mar 01 '16 at 22:45
@MikeC yes of course, thanks – isvforall Mar 01 '16 at 22:50

score 0 · Answer 2 · answered Mar 01 '16 at 22:45

Something like this might do the trick:

var arrayToSearch = ['apple', 'orange', 'pear', 'orange', 'orange', 'pear'];

countMatchingElements = function(arr, searchTerm) {
  return arr.filter(function(item) { return item === searchTerm; }).length;
};

document.writeln('"orange" appears ' + countMatchingElements(arrayToSearch, 'orange') + ' times.');

search an array for duplicates, javascript

2 Answers2