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var data = ['1', '2', '3', '4'], ret = [];
var count = Math.pow(2, data.length) - 1;
for(var i = 1; i <= count; i++){
ret[i] = '';
var n = 0, k = i;
while(k){
if (k & 1) ret[i] += data[n];
k >>= 1;
n++;
}
}
ret.shift();
console.log(ret);