Answers for "how duplicates works in javascript"

get duplicate values from array javascript

// This code was pasted by ProgrammerRimon, 2022-02-18
// Find dublicates numbers from array;

const a = [1,1,1,3,3,4,5,5,6,7,8,8,8,8,8,9,2];

function findDublicatesNumbersFromArray(a) {
    var d = [];
    for (let i = 0; i < a.length; i++) {
        var ct = a[i];
        var cmt = 0;
        for(var x = 0; x<a.length;++x) {
            if(ct === a[x]) {
                cmt++
                if(cmt > 1) {
                    d.push(a[i])
                }
            }
        }
    }
    return d.filter((i, ix)=> d.indexOf(i) === ix);
}

console.log(findDublicatesNumbersFromArray(a))

duplicate numbers in an array javascript

[1, 1, 2, 2, 3].filter((element, index, array) => array.indexOf(element) !== index) // [1, 2]