Run results for: map vs arr

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36

Browser: Chrome 57

Operating system: Windows

Device Platform: Other

Date tested: 7 years ago

Test name	Executions per second
map	169.6 Ops/sec
arr	9.8 Ops/sec

Script Preparation code:

var a1 = [];
for (var f = 0; f < 20000; f++) {
    var newNo = Math.floor(Math.random()*60000+10000);
    a1.push({id: newNo, name: 'test'});
}

Tests:

map
var unique = {}; a1.filter((row) =>{ var id = row.id; if(!unique[id]){ unique[id] = 1; return true; }else{ return false; } });
arr
var unique1 = []; a1.filter((row) => { var id = row.id; if(unique1.indexOf(id) === -1){ unique1.push(id); return true; }else{ return false; } });