What does .split() return if the string has no match?

Question

In this JavaScript code if the variable data does not have that character . then what will split return?

x = data.split('.'); 

Will it be an array of the original string?

Answer 1

Yes, as per ECMA262 15.5.4.14 String.prototype.split (separator, limit), if the separator is not in the string, it returns a one-element array with the original string in it. The outcome can be inferred from:

Returns an Array object into which substrings of the result of converting this object to a String have been stored. The substrings are determined by searching from left to right for occurrences of separator; these occurrences are not part of any substring in the returned array, but serve to divide up the String value.

If you're not happy inferring that, you can follow the rather voluminous steps at the bottom and you'll see that's what it does.

Testing it, if you type in the code:

alert('paxdiablo'.split('.')[0]); 

you'll see that it outputs paxdiablo, the first (and only) array element. Running:

alert('pax.diablo'.split('.')[0]); alert('pax.diablo'.split('.')[1]); 

on the other hand will give you two alerts, one for pax and one for diablo.