benchmark for array.join and +

benchmark.js

function plus(count) {
  var s = 'apple';
  var start = Date.now();
  var result = '';
  for (var i=0; i<count; i++) result += s;
  console.log(Date.now()-start)
}
 
function concat(count) {
  var s = 'apple';
  var start = Date.now();
  var result = [];
  for (var i=0; i<count; i++) result[i] = s;
  result.join('');
  console.log(Date.now()-start)
}
 
 
var c = 1000000;
plus(c);
concat(c);

result.markdown

c = 100:

plus: 12ms

concat: 0ms

c = 10*000:

plus: 14ms

concat: 1ms

c = 100*1000

plus: 23ms

concat: 12ms

c = 500*1000

plus: 70ms !!!

concat: 70ms !!!

c = 1010001000

plus: 1355ms

concat: 1657ms