// filterProperty i.e. 'id' or 'name' function GetDuplicates(array, filterProperty) { //lookup with our intended filter to get the duplicates by a given property const lookup = array.reduce((a, e) => { a[e.filterProperty] = ++a[e.filterProperty] || 0; return a; }, {}); let duplicates = array.filter(e => lookup[e.filterProperty]); return duplicates; }
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