Javascript objects are excellent for this purpose, since they are essentially key/value stores:

// Words to match

var words = [dell, ledl, abc, cba];



// The output object

var anagrams = {};



for (var i in words) {

    var word = words[i];



    // sort the word like you've already described

    var sorted = sortWord(word);



    // If the key already exists, we just push

    // the new word on the the array

    if (anagrams[sorted] != null) {

        anagrams[sorted].push(word);

    } 

    // Otherwise we create an array with the word

    // and insert it into the object

    else {

        anagrams[sorted] = [ word ];

    }

}



// Output result

for (var sorted in anagrams) {

    var words = anagrams[sorted];

    var sep = ,;

    var out = ;

    for (var n in words) {

        out += sep + words[n];

        sep = ;

    }

    document.writeln(sorted + :  + out + <br />);

}