Change Text Color of Selected Option in a Select B

问题:

I have a select box. The options have been styled with different colors via a CSS file that has been referenced. I want to be able to select an option and change the text color of the closed select box to the color of the chosen option.

<select id="mySelect" class="yellowText">
    <option class="greenText" value="apple" >Apple</option>
    <option class="redText" value="banana" >Banana</option>
    <option class="blueText" value="grape" >Grape</option>
</select>

So if I select Banana, the text should change from yellow to red.

I have tried:

onchange="this.style.color = this.options[this.selectedIndex].style.color;"

But this only works if I define my styles within the option tags inside html document.

I have also tried JavaScript:

function setSelectColor(thisElement){
    var thisElem = document.getElementById(thisElement);
    var thisOption = thisElem.options[thisElem.selectedIndex];
    var newColor = getStyle(thisOption,"color");
    alert("New Color: "+ newColor);
}

But this always returns the color: white. The getStyle function works everywhere else I use it so I do not believe that's the problem.

I got getStyle from this very website:

function getStyle(oElm, strCssRule){
    var strValue = "";
    if(document.defaultView && document.defaultView.getComputedStyle){
        strValue = document.defaultView.getComputedStyle(oElm, "").getPropertyValue(strCssRule);
    }
    else if(oElm.currentStyle){
        strCssRule = strCssRule.replace(/\-(\w)/g, function (strMatch, p1){
            return p1.toUpperCase();
        });
        strValue = oElm.currentStyle[strCssRule];
    }
    return strValue;
}

How can I solve this with JavaScript?

回答1:

Try this:

.greenText{ background-color:green; }

.blueText{ background-color:blue; }

.redText{ background-color:red; }

<select
    onchange="this.className=this.options[this.selectedIndex].className"
    class="greenText">
     <option class="greenText" value="apple" >Apple</option>
    <option class="redText"   value="banana" >Banana</option>
    <option class="blueText" value="grape" >Grape</option>
</select>

回答2:

ONE COLOR CASE - CSS only

Just to register my experience, where I wanted to set only the color of the selected option to a specific one.

I first tried to set by css only the color of the selected option with no success.

Then, after trying some combinations, this has worked for me with SCSS:

select {
      color: white; // color of the selected option

      option {
        color: black; // color of all the other options
      }
 }

Take a look at a working example with only CSS:

select {
  color: yellow; // color of the selected option
 }

select option {
  color: black; // color of all the other options
}

<select id="mySelect">
    <option value="apple" >Apple</option>
    <option value="banana" >Banana</option>
    <option value="grape" >Grape</option>
</select>

For different colors, depending on the selected option, you'll have to deal with js.

回答3:

You could do it like this.

jsFiddle

JS

var select = document.getElementById('mySelect');
select.onchange = function () {
    select.className = this.options[this.selectedIndex].className;
}

CSS

.redText {
    background-color:#F00;
}
.greenText {
    background-color:#0F0;
}
.blueText {
    background-color:#00F;
}

You could use option { background-color: #FFF; } if you want the list to be white.

HTML

<select id="mySelect" class="greenText">
    <option class="greenText" value="apple" >Apple</option>
    <option class="redText"   value="banana" >Banana</option>
    <option class="blueText" value="grape" >Grape</option>
</select>

Since this is a select it doesn't really make sense to use .yellowText as none selected if that's what you were getting at as something must be selected.

回答4:

JQuery Code:

$('#mySelect').change(function () {
    $('#mySelect').css("background", $("select option:selected").css("background-color"));
});

This will replace the select's background-color with selected option's background-color.

Here is an example fiddle.

回答5:

<html>
  <style>
.selectBox{
 color:White;
}
.optionBox{
  color:black;
}

</style>
<body>
<select class = "selectBox">
  <option class = "optionBox">One</option>
  <option class = "optionBox">Two</option>
  <option class = "optionBox">Three</option>
</select>