If you are appending to the dom [].join happens to be the most performant
This is a bit unclear, because it doesn't have anything to do with the dom specifically; [].join is just faster than string1 += string2 when you are building up a large string in a loop (probably because of having to allocate lots of string objects).
Having said that, I updated the tests, and += actually outperforms [].join in this test case. Perhaps join only takes the lead when the number of loop iterations gets significantly higher.
In section 9i on multiline strings, you say that
This is a bit unclear, because it doesn't have anything to do with the dom specifically; [].join is just faster than string1 += string2 when you are building up a large string in a loop (probably because of having to allocate lots of string objects).
Having said that, I updated the tests, and += actually outperforms [].join in this test case. Perhaps join only takes the lead when the number of loop iterations gets significantly higher.