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HTML

Given an array populated with numbers as a function parameter, produce a resulting array which contains any duplicates number from the array. For example, given the array [ 1, 2, 4, 4, 3, 3, 1, 5, 3 ] it should return [1, 4, 3].

JavaScript

var numbers = [1, 2, 4, 4, 3, 3, 1, 5, 3];
var duplicates = [];

function goThroughArray(arr) {
    for(var i = 0;i <= arr.length; i++) {
        if() {
        }
        duplicates += arr[i];
    }
    return duplicates;
}

alert(goThroughArray(numbers));