Convert permute method from Java to JavaScript

Question

I implemented a Java code for permutation combination a string with input str= "word1 word2 word3" then output as:

arr[0]= "word1 word2"

arr[1]= "word1 word3"

arr[2]= "word1 word2 word3"

arr[3]= "word2 word1"

arr[4]= "word2 word1 word3"

arr[5]= "word2 word3 word1"

arr[6]= "word3 word1"

arr[7]= "word3 word1 word2"

arr[8]= "word3 word2 word1"

This is Java code:

private static void permute(String[] ss, boolean[] used, String res, int level, List<String> list) {

    if (level == ss.length && res != ""){
        list.add(res);
    return;
    }

    for (int i = 0; i < ss.length; i++) {
        // Check if the string is currently used
        if (used[i]) {
            continue;
        }
        // Check if res is empty or a single word
        if(level > 1)
            list.add(res);
            used[i] = true;
            permute(ss, used, res + " " + ss[i], level + 1, list);
            used[i] = false;
        }
    }

public static List<String> PermuteWords(String s){
    String[] ss = s.split(" ");
    boolean[] used = new boolean[ss.length];
    String res = "";
    List<String> list = new ArrayList<String>();
    permute(ss, used, res, 0, list);
    return list;
}

When converting to JS code, I don't know what are errors in this code:

function permute(ss, used, res, level, list){
  if(level==ss.lenght&&res!==""){
      list.add(res);
      return;
  }

  for(var i=0; i<ss.lenght; i++){
      if (used[i]===true){
        continue;
      }

      if(level>1){
        list.add(res);
        used[i]=true;
        permute(ss, used, res+" "+ss[i], level+1, list)
        used[i]=false;
      }
    }
}
function permuteword(s){
  var ss;
  for(var i=0; i<s.length;i++){
      ss[i]=s[i];
  }
  var used;
  for(var j=0; j<s.length;j++){
      used[j]=false;
  }
  var result;
  permute(ss, used, res, 0, result);
  return result;
}

Answer 1

Java and Javascript may sound almost the same but they aren't. They take different appoaches doing different things. If in Java You are checking the console for errors on running the program, then in Javascript you can check for the errors in the browser console (open console with F12)

POPULATE ARRAY
Javascript arrays don't have add() method. To add a value to it, use push:
list.push(res)

POPULATE ARRAY #2
In permuteword() function you are trying to populate variable ss that is not initialized. Compiler doesn't understand where you want to put that value. Initialize ss as an empty array:
var ss = [];

TYPOs
In the first for loop you have ss.lenght. Fix that. Always check for the typos.

EXTRA
In permuteword() you are passing res to the permute() function although you don't have it defined in the function. Things will work if res is a global variable defined outside of the functions.

---

And take advantage of that browser console. Every Javascript developer (from noobie to pro) has it always open!

Answer 2

I ran the code in couchdb and cloudant that showed the general errors that i missed checking the syntax. I modified the code as:

function permute(ss, used, res, level, list){
  if(level==ss.lenght&&res!==""){
      list.push(res);
      return;
  }

  for(var i=0; i<ss.length; i++){
      if (used[i]===true){
        continue;
      }

      if(level>1){
        list.push(res);
        used[i]=true;
        permute(ss, used, res+" "+ss[i], level+1, list)
        used[i]=false;
      }
    }
}
function permuteword(s){
  var ss=[];

  for(var i=0; i<s.length;i++){
      ss[i]=s[i];
  }

  var used=[];
  for(var j=0; j<s.length;j++){
      used[j]=false;
  }
  res="";

  var result=[];
  permute(ss, used, res, 0, result);
  return result;
}

function(doc){
  var list=permuteword("word1 word2 word3");
  for(var i=0; i<list.length; i++){
      index("default", list[i],{store, true});
  }
}

However, i still meet the errors as:

{"error":"{nocatch,{compilation_error,<<\"Expression does not eval to a function. ((new String(\\"function permute(ss, used, res, level, list){\\r\\n if(level==ss.lenght&&res!==\\\\"\\\\"){\\r\\n list.push(res);\\r\\n return;\\r\\n }\\r\\n\\r\\n for(var i=0; i1){\\r\\n list.push(res);\\r\\n used[i]=true;\\r\\n permute(ss, used, res+\\\\" \\\\"+ss[i], level+1, list)\\r\\n used[i]=false;\\r\\n }\\r\\n }\\r\\n}\\r\\nfunction permuteword(s){\\r\\n var ss=[];\\r\\n ss=s.split(\\\\" \\\\");\\r\\n var used=[];\\r\\n for(var j=0; j>}}","reason":"[{couch_os_process,prompt,3,[{file,\"src/couch_os_process.erl\"},{line,65}]},\n {dreyfus_index_updater,update,2,\n [{file,\"src/dreyfus_index_updater.erl\"},{line,42}]}]"}