Question

How to print the duplicate elements of an array in JavaScript

Answer 1

function printDuplicates(arr) {
    const object = {};
 
    arr.forEach(function (item) {
        if (!object[item])
             object[item] = 0;
        object[item] += 1;
    })
 
    for (const val in object) {
           if (object[val] >= 2) {
              console.log(val);
           }
        }
}
 
const arr = [3, 5, 9, 1, 7, 8, 1, 9, 0, 3, 9];
 
printDuplicates(arr);
 
 
 
 
/*
run:

"1"
"3"
"9"
 
*/

 

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