Run results for: Symbol vs String property access speed

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/138.0.0.0 Safari/537.36

Browser: Chrome 138

Operating system: Mac OS X 10.15.7

Device Platform: Desktop

Date tested: 9 months ago

Test name	Executions per second
Symbol read	14146.6 Ops/sec
Symbol read prototype	143245.4 Ops/sec
Symbol write	137070.9 Ops/sec
Symbol overwrite	13982.1 Ops/sec
Symbol overwrite prototype	143722.6 Ops/sec
String read	156086.5 Ops/sec
String read prototype	129474.4 Ops/sec
String write	13783.9 Ops/sec
String overwrite	14032.6 Ops/sec
String overwrite prototype	139815.2 Ops/sec

Script Preparation code:

var strings = [];
var symbols = [];
var stringMap = {__proto__: null};
var symbolMap = {__proto__: null};
var emptyMap = {__proto__: null};
for (let i = 0; i < 1000; i++) {
  strings[i] = `foobar${i}`;
  symbols[i] = Symbol(`foobar${i}`);
  stringMap[strings[i]] = i;
  symbolMap[symbols[i]] = i;
}
var stringProtoMap = {__proto__: stringMap};
var symbolProtoMap = {__proto__: symbolMap};
function mapRead(map, keys) {
  let total = 0;
  for (const key of keys) {
    total += map[key];
  }
  return total;
}
function mapWrite(map, keys) {
  for (const key of keys) {
    map[key] = true;
  }
}

Tests:

Symbol read
mapRead(symbolMap, symbols)
Symbol read prototype
mapRead(symbolProtoMap, symbols);
Symbol write
mapWrite(emptyMap, symbols);
Symbol overwrite
mapWrite(symbolMap, symbols);
Symbol overwrite prototype
mapWrite(symbolProtoMap, symbols);
String read
mapRead(stringMap, strings);
String read prototype
mapRead(stringProtoMap, strings);
String write
mapWrite(stringMap, strings);
String overwrite
mapWrite(stringMap, strings);
String overwrite prototype
mapWrite(stringProtoMap, strings);

Run results for: Symbol vs String property access speed

Testing JS square-bracket property access by string and by similarly-named symbol

Symbol read

Symbol read prototype

Symbol write

Symbol overwrite

Symbol overwrite prototype

String read

String read prototype

String write

String overwrite

String overwrite prototype