新手上路,js一个数组各项组合的算法

Question

letarr=[1,2,3,4];(arr的长度不固定)求[1,2,3,4,12,13,14,23,24,34]

Answer 1

varnewArr=[];
for(vari=0;inewArr.push(arr[i]);
for(varx=i+1;xnewArr.push(arr[i]+''+arr[x]);
}
}