How to find duplicates in key value pairs array sails.js

Question

I have an array as below.

[emails] => Array (
   [0] => Array (
      [a] => a@a.com
      [is_verified_a] => 1
    )
   [1] => Array (
      [b] => a@a.com
      [is_verified_b] => 1
   )
),

I need to find duplicates in this array , but keys are different ie a and b have the same email 'a@a.com'.

ie , Have to check for duplicates in this array and need only the value 'a@a.com' in a separate variable. Is there any way to find out using _.uniq or any other underscore functions?

Please help.Thanks a lot.

Answer 1

What you want to do is not clear. However since you're using JavaScript your array should look like:

var emails = [
    {
        email: "a@a.com",
        verified: true,
        key: "a"
    },
    {
        email: "a@a.com",
        verified: true,
        key: "b"
    }
];

It makes no sense to encode keys in your objects separately (especially not in property names).

To remove duplicates from an array we can create a generic removeDuplicatesBy function:

function removeDuplicatesBy(comparator, array) {
    var length = array.length;
    var unique = [];

    for (var i = 0; i < length; i++) {
        var element = array[i];
        var isUnique = true;

        for (var j = 0; j < i; j++) {
            if (comparator(element, array[j])) {
                isUnique = false;
                break;
            }
        }

        if (isUnique) unique.push(element);
    }

    return unique;
}

Now we can remove duplicates in the emails array as follows:

var uniqueEmails = removeDuplicatesBy(function (a, b) {
    return a.email === b.email && a.verified === b.verified;
}, emails);

If you need to maintain keys in your objects then you're probably doing something wrong. You should consider restructuring your code.