Compares building a string with += concatenation against Array.prototype.join for assembling many pieces.
var iterations = 20000;
var parts=Array.from({length:100},function(_,i){return "x"+i});var r="";for(var i=0;i<parts.length;i++){r+=parts[i]}parts.join("")var r="";for(var i=0;i<parts.length;i++){r+=parts[i]}parts.join("")var r="";for(var i=0;i<parts.length;i++){r+=parts[i]}parts.join("")| Browser | Snippet A | Snippet B | Winner |
|---|---|---|---|
1st  Microsoft Edge154.0.4258.37 | 5.10 ms | 6.30 ms | Snippet A1.24× faster |
2nd  Firefox158.0 | 7.00 ms | 8.00 ms | Snippet A1.14× faster |
3rd  Chrome155.0.8059.39 | 10.40 ms | 13.50 ms | Snippet A1.30× faster |
4th  Safari26.6.2 | 20.00 ms | 28.00 ms | Snippet A1.40× faster |
Median of 5 trials × 20,000 iterations per snippet.