Run results for: JS String '+' short v.s. long strings

Run details:

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/109.0

Browser: Firefox 109

Operating system: Mac OS X 10.15

Device Platform: Desktop

Date tested: 2 years ago

Benchmark engine: Benchmark.js

Add short string each loop

378K/s

Add long string each loop

372K/s

View exact numbers

Test name	Executions per second
✓ Add short string each loop	378,145 Ops/sec
Add long string each loop	371,562 Ops/sec

Script Preparation code:

var nLoops = 1000;
var shortString = "aAbBcCdDeEfFgGhHiIjJkKlLmMnNoOpPqQrRsStTuUvVwWxXyYzZ"; // 52 characters
var longString = '';

for (var i = 0; i < 40; i++) {
  longString += shortString; // 52 characters x 40 = 2,080 characters
}

Tests:

Add short string each loop
var str = ''; for (var i = 0; i < nLoops; i++) { str += shortString; }
Add long string each loop
var str = ''; for (var i = 0; i < nLoops; i++) { str += longString; }

Run results for: JS String '+' short v.s. long strings

Does the size of the string concatenated affect the performance?

Add short string each loop

Add long string each loop