Run results for: Symbol vs String property access speed

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:122.0) Gecko/20100101 Firefox/122.0

Browser: Firefox 122

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Symbol overwrite

57K/s

Symbol read prototype

55K/s

Symbol read

55K/s

Symbol write

55K/s

Symbol overwrite prototype

52K/s

String read

21K/s

String read prototype

21K/s

String overwrite prototype

21K/s

String overwrite

21K/s

String write

20K/s

View exact numbers

Test name	Executions per second
✓ Symbol overwrite	56,755 Ops/sec
Symbol read prototype	55,009 Ops/sec
Symbol read	54,982 Ops/sec
Symbol write	54,854 Ops/sec
Symbol overwrite prototype	52,183 Ops/sec
String read	21,208 Ops/sec
String read prototype	21,203 Ops/sec
String overwrite prototype	20,608 Ops/sec
String overwrite	20,512 Ops/sec
String write	19,907 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