RegEx that will match the last occurrence of dot in a string

Question

I have a filename that can have multiple dots in it and could end with any extension:

tro.lo.lo.lo.lo.lo.png

I need to use a regex to repla

Answer 1

Why not simply split the string and add said suffix to the second to last entry:

var arr = 'tro.lo.lo.lo.lo.lo.zip'.split('.');
arr[arr.length-2] += '@2x';
var newString = arr.join('.');