Change dropdown selected text without changing the option text

I have an indented dropdownlist, where I have some root options and their children, like below:

Food
    Market
    Restaurants
    Grossery
Clothes
Home
    TV

If I select Market, for example, the text in the dropdownlist still indented. Then I did a jQuery function to remove the spaces before the text. It looks like this:

$(function () {
    $("select").change(function () {
        var str = jQuery.trim($("select option:selected").text());

        $("select option:selected").text(str);
    })
}); 

It works. But, if I try to select other option after selected Market, for example, The list looks like this:

Food
Market
    Restaurants
    Grossery
Clothes
Home
    TV

Market lost its indentation. I would like a way to remove the spaces but only in开发者_开发知识库 the selected text shown in the dropdown, but not in the option.

What should I do?

Bit late to the party here...

First of all I've amended your HTML to include a class on each option element to indicate the level to which it should be indented.

<select class="select">
    <option value="1" class="level-0">Item 1</option>
    <option value="2" class="level-1">Item 1.1</option>
    <option value="3" class="level-2">Item 1.1.1</option>
    <option value="4" class="level-1">Item 1.2</option>
</select>

I have also written the jQuery to add the required indentation on load, using a string of non-breaking spaces. While this is hardly an elegant solution, it's the only one that will work across all browsers - as you've obviously discovered, OPTION elements are a land CSS forgot. It also includes the logic for the change event to remove/add the padding to the selected items.

While it's not the prettiest code, and I'm sure there are a lot of performance improvements which could be made (hey, it's late here and this was a brain dump as I was intrigued by the question), it works.

var levelClassPrefix = "level-";
var indentationString = "    ";

$(".select").each(function() {
    padOptions(this);
});

function padOptions(elem) {
    $("OPTION", elem).each(function() {
        var level = $(this).attr("class").replace(levelClassPrefix, "");
        var currentText = $(this).html();
        var regex = new RegExp(indentationString , "g");
        $(this).html(padText(currentText.replace(regex, ""), level))
    });        
}

function padText(value, level) {
    var output = "";
    for (var i = 1; i <= level; i++) {
        output = output + indentationString;
    }
    return output + value;
}

$(".select").change(function() {
    padOptions(this);

    var selectedOption = $("option:selected", this);
    var currentText = selectedOption .html();
    var regex = new RegExp(indentationString , "g");
    selectedOption.text(currentText.replace(regex, ""));
});

Here is a fiddle to prove the theory

Why not style the indivudual options instead?

Something along these lines:

HTML:

<select>
    <option>Food</option>
    <option class='sub'>Market</option>
    <option class='sub'>Restaurants</option>
    <option class='sub'>Grossery</option>
    <option>Clothes</option>
    <option>Home</option>
    <option class='sub'>TV</option>
</select>

CSS:

option.sub { text-indent: 2em; }

Why trim the string? I would add a css class similar to this

select .level0 {}

select.level1 {
    text-indent: -1.5em; /* you have to calculate your indentation value */
}

select.level2 {
    text-indent: -3em; /* you have to calculate your indentation value */
}

Forge html accordingly

<select>
    <option class='level0'>Food</option>
    <option class='level1'>Market</option>
    <option class='level1'>Restaurants</option>
    <option class='level1'>Grossery</option>
    <option class='level0'>Clothes</option>
    <option class='level0'>Home</option>    
    <option class='level1'>TV</option>
</select>

and apply the class accordingly. Maybe, I don't know jquery, you have to

$(function () {
    $("select").change(function () {
        var theclass = $("select option:selected").class();
        $("select option:selected").set(class, theClass); // <-- is this jquery??
    })
});