how to genrate all combination of string in js code example

Example 1: JavaScript function that generates all combinations of a string.

function combu(s){
var buff = [];
var res = [];
for (i=0;i<s.length;i++){
    buff = [s[i]];
    var index=0;
    while(res[index]){
        buff.push(''+res[index]+s[i]);
        index++;
    }
    res = res.concat(buff);
}
return res;
}

combu('abc');

Example 2: JavaScript function that generates all combinations of a string.

function combString(str){
     var lenStr = str.length;
     var result = [];
     var indexCurrent = 0;

     while(indexCurrent < lenStr){
         var char = str.charAt(indexCurrent);
         var x;
         var arrTemp = [char];

         for(x in result) {
             arrTemp.push(""+result[x]+char);
         }
         result = result.concat(arrTemp);

         indexCurrent++;
     }

     return result;
}

console.log(combString("abc"));