Random list splitter

Split a delimited list (comma, tab, new line and semi-colon) randomly into a number of sublists.

by swc23

HTML

<div id="main-content">
    <form>Step 1: How is the original list delimited?
        <br>
        <select id="delimiter">
            <option value="1">Comma</option>
            <option value="2">Tab</option>
            <option value="3">Semi-colon</option>
            <option value="4">New-line</option>
        </select>
        <br>
        <br>Step 2: Paste your original list here.
        <br>
        <textarea placeholder="e.g. apple,banana" id="original-list"></textarea>
        <br>
        <br>Step 3: How many lists do you want to split the list into?
        <br>
        <select id="numOfLists">
            <option>2</option>
            <option>3</option>
            <option>4</option>
            <option>5</option>
            <option>6</option>
            <option>7</option>
            <option>8</option>
            <option>9</option>
            <option>10</option>
        </select>lists
        <br>
        <br>
        <input type="submit" value="Go!" disabled>
    </form>
    <br>
    <div id="results"></div>
</div>

CSS

#main-content {
    font-family: verdana, arial;
}

textarea {
    border: 1px solid black;
    border-radius: 3px;
}

#original-list {
    width: 400px;
}

JavaScript

var form = $("#main-content form");
var textarea = $("textarea", form);
var results = $("#results");

function getOriginalList() {
    return $.trim(textarea.val());
}

function getPlaceholder() {
    switch ($("#delimiter").val()) {
        case "1":
            return "e.g. apple,banana";
        case "2":
            return "e.g. apple\tbanane";
        case "3":
            return "e.g. apple;banana";
        case "4":
            return "e.g. apple[enter]banana";
    }
}

function getJoinDelimiter() {
    switch ($("#delimiter").val()) {
        case "1":
            return ",";
        case "2":
            return "\t";
        case "3":
            return ";";
        case "4":
            return "\n";
    }
}

function getSplitRegex() {
    switch ($("#delimiter").val()) {
        case "1":
            return /,/;
        case "2":
            return /\t/;
        case "3":
            return /;/;
        case "4":
            return /\r\n|\r|\n/;
    }
}

function createLists() {
    var items = getOriginalList().split(getSplitRegex());
    var lists = [];
    var numOfLists = $("#numOfLists", form).val();
    for (var i = 0; i < numOfLists; i++) lists[i] = [];
    for (i = 0; i < items.length; i++) {
        lists[getRandomId(numOfLists)].push(items[i]);
    }
    // rendering the lists
    results.html("");
    var joinDelimiter = getJoinDelimiter();
    for (i = 0; i < numOfLists; i++) {
        createResultTextarea(lists[i].join(joinDelimiter));
    }
}

function createResultTextarea(list) {
    var newTextarea = $("<textarea></textarea>");
    newTextarea.val(list);
    results.append(newTextarea);
}

function getRandomId(max) {
    return Math.floor((Math.random() * max));
}

form.on("submit", function (e) {
    e.preventDefault();
    createLists();
});

textarea.on("keyup", function (e) {
    $("input[type=submit]", form).prop("disabled", !getOriginalList());
});

$("#delimiter").on("change", function() {
    textarea.attr("placeholder",...