Benchmark: JS Performance (const vs let vs var)

Script Preparation code:

const maxObjectSize = 10
const maxRuns = 1000000;

Tests:

CONST <> CONSTRUCTION
for (let i = 0; i < maxRuns; i++) { const x = i; }
CONST <> UPDATE
const x = {v: 0} for (let i = 0; i < maxRuns; i++) { x.v = 1; }
CONST <> DELETE
const x = {} for (let i = 0; i < maxObjectSize; i++) { x[`key_{i}`] = 1 } for (let i = 0; i < maxObjectSize; i++) { delete x[`key_{i}`] }
CONST <> ACCESS
const x = {} for (let i = 0; i < maxObjectSize; i++) { x[`key_{i}`] = 1 } for (let i = 0; i < maxObjectSize; i++) { console.log(x[`key_{i}`]); }
LET <> CONSTRUCTION
for (let i = 0; i < maxRuns; i++) { let x = i; }
LET <> UPDATE
let x = {v: 0} for (let i = 0; i < maxRuns; i++) { x.v = 1; }
LET <> DELETE
let x = {} for (let i = 0; i < maxObjectSize; i++) { x[`key_{i}`] = 1 } for (let i = 0; i < maxObjectSize; i++) { delete x[`key_{i}`] }
LET <> ACCESS
let x = {} for (let i = 0; i < maxObjectSize; i++) { x[`key_{i}`] = 1 } for (let i = 0; i < maxObjectSize; i++) { console.log(x[`key_{i}`]); }
VAR <> ASSIGNMENT
for (let i = 0; i < maxRuns; i++) { var x = i; }
VAR <> UPDATE
var x = {v: 0} for (let i = 0; i < maxRuns; i++) { x.v = 1; }
VAR <> ACCESS
var x = {} for (let i = 0; i < maxObjectSize; i++) { x[`key_{i}`] = 1 } for (let i = 0; i < maxObjectSize; i++) { console.log(x[`key_{i}`]); }
VAR <> DELETE
var x = {} for (let i = 0; i < maxObjectSize; i++) { x[`key_{i}`] = 1 } for (let i = 0; i < maxObjectSize; i++) { delete x[`key_{i}`] }

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
CONST <> CONSTRUCTION
CONST <> UPDATE
CONST <> DELETE
CONST <> ACCESS
LET <> CONSTRUCTION
LET <> UPDATE
LET <> DELETE
LET <> ACCESS
VAR <> ASSIGNMENT
VAR <> UPDATE
VAR <> ACCESS
VAR <> DELETE

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/109.0.0.0 Safari/537.36

Browser/OS: Chrome 109 on Windows

View result in a separate tab

CONST <> DELETE

2.8M/s

VAR <> DELETE

2.8M/s

LET <> DELETE

2.8M/s

LET <> ACCESS

35K/s

VAR <> ACCESS

34K/s

CONST <> ACCESS

33K/s

CONST <> UPDATE

854/s

CONST <> CONSTRUCTION

852/s

VAR <> UPDATE

852/s

LET <> CONSTRUCTION

852/s

VAR <> ASSIGNMENT

849/s

LET <> UPDATE

847/s

View exact numbers

Test name	Executions per second
✓ CONST <> DELETE	2,789,804 Ops/sec
VAR <> DELETE	2,778,016 Ops/sec
LET <> DELETE	2,768,529 Ops/sec
LET <> ACCESS	34,613 Ops/sec
VAR <> ACCESS	34,233 Ops/sec
CONST <> ACCESS	33,172 Ops/sec
CONST <> UPDATE	854 Ops/sec
CONST <> CONSTRUCTION	852 Ops/sec
VAR <> UPDATE	852 Ops/sec
LET <> CONSTRUCTION	852 Ops/sec
VAR <> ASSIGNMENT	849 Ops/sec
LET <> UPDATE	847 Ops/sec

JS Performance (const vs let vs var) (version: 1)

Comparing performance of: `CONST <> CONSTRUCTION vs CONST <> UPDATE vs CONST <> DELETE vs CONST <> ACCESS vs LET <> CONSTRUCTION vs LET <> UPDATE vs LET <> DELETE vs LET <> ACCESS vs VAR <> ASSIGNMENT vs VAR <> UPDATE vs VAR <> ACCESS vs VAR <> DELETE`

Created: one year ago by: Registered User

Go to the latest result

CONST <> CONSTRUCTION

CONST <> UPDATE

CONST <> DELETE

CONST <> ACCESS

LET <> CONSTRUCTION

LET <> UPDATE

LET <> DELETE

LET <> ACCESS

VAR <> ASSIGNMENT

VAR <> UPDATE

VAR <> ACCESS

VAR <> DELETE

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

JS Performance (const vs let vs var) (version: 1)

Comparing performance of: CONST <> CONSTRUCTION vs CONST <> UPDATE vs CONST <> DELETE vs CONST <> ACCESS vs LET <> CONSTRUCTION vs LET <> UPDATE vs LET <> DELETE vs LET <> ACCESS vs VAR <> ASSIGNMENT vs VAR <> UPDATE vs VAR <> ACCESS vs VAR <> DELETE

Created: one year ago by: Registered User

Go to the latest result

CONST <> CONSTRUCTION

CONST <> UPDATE

CONST <> DELETE

CONST <> ACCESS

LET <> CONSTRUCTION

LET <> UPDATE

LET <> DELETE

LET <> ACCESS

VAR <> ASSIGNMENT

VAR <> UPDATE

VAR <> ACCESS

VAR <> DELETE

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Related benchmarks

Comparing performance of: `CONST <> CONSTRUCTION vs CONST <> UPDATE vs CONST <> DELETE vs CONST <> ACCESS vs LET <> CONSTRUCTION vs LET <> UPDATE vs LET <> DELETE vs LET <> ACCESS vs VAR <> ASSIGNMENT vs VAR <> UPDATE vs VAR <> ACCESS vs VAR <> DELETE`