MeasureThat.net

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

Does the size of the string concatenated affect the performance?

Go to the benchmark
Run details:
Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/109.0
Firefox 109
Mac OS X 10.15
Desktop
one year ago
Test name Executions per second
Add short string each loop 378144.7 Ops/sec
Add long string each loop 371561.7 Ops/sec
Script Preparation code:
​x
 
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;
    }