Getting values from an HTMLCollection to a string

Question

I am attempting to grab the selected values of a multi-select dropdown and convert them into a single string for later manipulation. At the moment I have the following code:

HTML:

            <select id="genreList" multiple="multiple" name="addGenre[]"  style="width: 150px;font-size: 10pt;">
                <option value="Action">Action</option>
                <option value="Comedy">Comedy</option>
                <option value="Fantasy">Fantasy</option>
                <option value="Horror">Horror</option>
                <option value="Mystery">Mystery</option>
                <option value="Non-Fiction">Non-Fiction</option>
                <option value="Period">Period</option>
                <option value="Romance">Romance</option>
                <option value="Sci-Fi">Sci-Fi</option>
                <option value="Thriller">Thriller</option>
            </select></p>

            <p><input type="button" onclick="newComic()" value="Add Comic" id="btnAddComic" style="font-size: 10pt; width: 150px; height:40px;"></p>

JavaScript:

<script>
function newComic()
        {
            var elem = document.querySelector("#genreList").selectedOptions;
            var arr = [].slice.call(elem);
            var genres = arr.join(', ');
            window.alert(genres);
}
</script>

The alert window is currently outputting the following:

[object HTMLOptionElement, object HTMLOptionElement, ...]

where '...' represents any further hypothetical options.

What I need is for 'genres' to output as, for example, 'Action, Romance, Thriller' instead.

Thanks in advance for any help.

Answer 1

When you join the array, it is calling the "toString" of each element. In this case, they are DOM elements and return their type. You can use map first to create a new array of strings containing the value of each option:

http://jsfiddle.net/Lfx6r5sm/

var genres = arr.map(function(el){
    return el.value;
}).join(', ');

Answer 2

You could iterate through the selected items like so:

<script type="text/javascript">
function newComic(){
    var elem = document.querySelector("#genreList").selectedOptions;
    var arr = [];
    for(var x=0; x<elem.length; x++){
        // for the TEXT value
        //arr.push(elem[x].text);

        // for the value
        arr.push(elem[x].value);
    }
    var genres = arr.join(', ');
    window.alert(genres);
}
</script>

Answer 3

You need to iterate through HTMLCollection like this

<script>
    function newComic()
    {
       var elem = document.querySelector("#genreList").selectedOptions;
       console.log(elem);
       for (var i = 0; i < elem.length; i++) {
           console.log(elem[i].attributes[0].nodeValue); //second console output
       }
    }
</script>

Answer 4

I think jquery is best suited for this task.

HTML

<select id="genreList" multiple="multiple" name="addGenre[]"  style="width: 150px;font-size: 10pt;">
            <option value="Action">Action</option>
            <option value="Comedy">Comedy</option>
            <option value="Fantasy">Fantasy</option>
            <option value="Horror">Horror</option>
            <option value="Mystery">Mystery</option>
            <option value="Non-Fiction">Non-Fiction</option>
            <option value="Period">Period</option>
            <option value="Romance">Romance</option>
            <option value="Sci-Fi">Sci-Fi</option>
            <option value="Thriller">Thriller</option>
</select>

<p><input type="button" value="Add Comic" id="btnAddComic" style="font-size: 10pt; width: 150px; height:40px;"></p>

jQuery

$("#btnAddComic").click(function(){
    var inz = $( "#genreList option:selected" ).map(function(){
        return $(this).text();
    }).get().join(',');
    alert(inz);
});

SEE THE FIDDLE

http://jsfiddle.net/inzamamtahir/1bm45gu7/2/