Why does string.split with a regular expression that contains a capturing group return an array that ends with an empty string?

Question

I\'d like to split an input string on the first colon that still has characters after it on the same line.

For this, I am using the regular expression /:(.+)/<

Answer 1

My regexp always generates an extra element at the end of the array returned by string.prototype.split(). So I simply truncate the array every time. Seems better than Array.filter when it's always the last element that is removed. I'm parsing CSS/SVG transforms, splitting on both left and right parentheses. Either of these works: /\(|\)/ or /[\(\)]/.
For example:

arr = "rotate(90  46  88) scale(1.2 1.2)".split(/\(|\)/);
arr.length--;

Or if you want to get fancy and cram it into one line:

(arr = "rotate(90  46  88) scale(1.2 1.2)".split(/\(|\)/)).length--;

The result is: ["rotate","90 46 88","scale","1.2 1.2"]