Run results for: Map lookup vs array index lookup

Run details:

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0

Browser: Firefox 78

Operating system: Linux

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Map lookup	137.3 Ops/sec
Array lookup	7757.0 Ops/sec

Script Preparation code:

var map = new Map();
var arrLookup = [];
var items = [];

for (var i = 0; i < 100; i++) {
  	items[i] = [];
	for (var j = 0; j < 100; j++) {
      	items[i][j] = [i,j];
		if (Math.random() < 0.1) {
        	map.set(i+","+j, Math.random()>=0.5);
          	if (!arrLookup[i]) arrLookup[i] = [];
          	arrLookup[i][j] = Math.random()>=0.5;
		}
	}
}

​x
 
​var map = new Map();var arrLookup = [];var items = [];​for (var i = 0; i < 100; i++) {    items[i] = [];    for (var j = 0; j < 100; j++) {        items[i][j] = [i,j];        if (Math.random() < 0.1) {            map.set(i+","+j, Math.random()>=0.5);            if (!arrLookup[i]) arrLookup[i] = [];            arrLookup[i][j] = Math.random()>=0.5;        }    }}

Tests:

Map lookup

var results = [], i, j;
for (i = 0; i < 100; i++) {
	for (j = 0; j < 100; j++) {
		if (map.has(items[i][j]	+"")) results.push(map.get(items[i][j]+""));
    }
}
if (results.length === 0) throw Error();

 
var results = [], i, j;for (i = 0; i < 100; i++) {    for (j = 0; j < 100; j++) {        if (map.has(items[i][j] +"")) results.push(map.get(items[i][j]+""));    }}if (results.length === 0) throw Error();

Array lookup

var results = [], i, j;
for (i = 0; i < 100; i++) {
	for (j = 0; j < 100; j++) {
    	if (arrLookup[i] && typeof arrLookup[i][j] !== "undefined") results.push(arrLookup[i][j]);
    }
}
if (results.length === 0) throw Error();

 
var results = [], i, j;for (i = 0; i < 100; i++) {    for (j = 0; j < 100; j++) {        if (arrLookup[i] && typeof arrLookup[i][j] !== "undefined") results.push(arrLookup[i][j]);    }}if (results.length === 0) throw Error();