jquery - Recursively Concatenate Strings in Array JavaScript

Question

I have an array of type String in Javascript. Eg: ["ab", "cd", "ef", "gh"] This array is not fixed & is alphabetically ordered.

I want an output like this:

ab
abcd
abef
abgh
abcdef
abcdgh
abefgh
abcdefgh

cd
cdef
cdgh
cdefgh

ef
efgh

Answer 1

Use this for creating the power set of x:

function power(x) {
    var r = [""], // start with empty set/string
        l = 1;
    for (var i=0; i<x.length; l=1<<++i) // OK, l is just r[i].length, but this looks nicer :)
        for (var j=0; j<l; j++) {
            r.push(r[j].slice(0)); // copy
            r[j] += x[i];
        }
    return r;
}

Usage:

> power(["ab", "cd", "ef", "gh"])
["abcdefgh", "cdefgh", "abefgh", "efgh", "abcdgh", "cdgh", "abgh", "gh", "abcdef", "cdef", "abef", "ef", "abcd", "cd", "ab", ""]