我正在使用jans片段的ryan fait
http://ryanfait.com/resources/custom-checkboxes-and-radio-buttons/
当我在网站上提交表单并且必填字段为空时，我将输入的背景颜色（例如）从白色更改为红色！到目前为止一切都好......
我的表格中也有一个选择框。选择框将被 class =“styled”替换为imagebackground。 （工作得很好）
<select id="name" name="name" class="styled">
<option value="1" selected="selected">Please select an option</option>
<option value="2" >option 1</option>
<option value="3" >option 2</option>
</select>
但是当我离开时，例如选择框为空并提交表格我也想要一个红色背景。
有没有办法2修改js-code，其中我有一个select.gif和一个select_error.gif作为background-image
/*
CUSTOM FORM ELEMENTS
Created by Ryan Fait
www.ryanfait.com
The only things you may need to change in this file are the following
variables: checkboxHeight, radioHeight and selectWidth (lines 24, 25, 26)
The numbers you set for checkboxHeight and radioHeight should be one quarter
of the total height of the image want to use for checkboxes and radio
buttons. Both images should contain the four stages of both inputs stacked
on top of each other in this order: unchecked, unchecked-clicked, checked,
checked-clicked.
You may need to adjust your images a bit if there is a slight vertical
movement during the different stages of the button activation.
The value of selectWidth should be the width of your select list image.
Visit http://ryanfait.com/ for more information.
*/
var checkboxHeight = "25";
var radioHeight = "25";
var selectWidth = "190";
/* No need to change anything after this */
document.write('<style type="text/css">input.styled { display: none; } select.styled { position: relative; width: ' + selectWidth + 'px; opacity: 0; filter: alpha(opacity=0); z-index: 5; } .disabled { opacity: 0.5; filter: alpha(opacity=50); }</style>');
var Custom = {
init: function() {
var inputs = document.getElementsByTagName("input"), span = Array(), textnode, option, active;
for(a = 0; a < inputs.length; a++) {
if((inputs[a].type == "checkbox" || inputs[a].type == "radio") && inputs[a].className == "styled") {
span[a] = document.createElement("span");
span[a].className = inputs[a].type;
if(inputs[a].checked == true) {
if(inputs[a].type == "checkbox") {
position = "0 -" + (checkboxHeight*2) + "px";
span[a].style.backgroundPosition = position;
} else {
position = "0 -" + (radioHeight*2) + "px";
span[a].style.backgroundPosition = position;
}
}
inputs[a].parentNode.insertBefore(span[a], inputs[a]);
inputs[a].onchange = Custom.clear;
if(!inputs[a].getAttribute("disabled")) {
span[a].onmousedown = Custom.pushed;
span[a].onmouseup = Custom.check;
} else {
span[a].className = span[a].className += " disabled";
}
}
}
inputs = document.getElementsByTagName("select");
for(a = 0; a < inputs.length; a++) {
if(inputs[a].className == "styled") {
option = inputs[a].getElementsByTagName("option");
active = option[0].childNodes[0].nodeValue;
textnode = document.createTextNode(active);
for(b = 0; b < option.length; b++) {
if(option[b].selected == true) {
textnode = document.createTextNode(option[b].childNodes[0].nodeValue);
}
}
span[a] = document.createElement("span");
span[a].className = "select";
span[a].id = "select" + inputs[a].name;
span[a].appendChild(textnode);
inputs[a].parentNode.insertBefore(span[a], inputs[a]);
if(!inputs[a].getAttribute("disabled")) {
inputs[a].onchange = Custom.choose;
} else {
inputs[a].previousSibling.className = inputs[a].previousSibling.className += " disabled";
}
}
}
document.onmouseup = Custom.clear;
},
pushed: function() {
element = this.nextSibling;
if(element.checked == true && element.type == "checkbox") {
this.style.backgroundPosition = "0 -" + checkboxHeight*3 + "px";
} else if(element.checked == true && element.type == "radio") {
this.style.backgroundPosition = "0 -" + radioHeight*3 + "px";
} else if(element.checked != true && element.type == "checkbox") {
this.style.backgroundPosition = "0 -" + checkboxHeight + "px";
} else {
this.style.backgroundPosition = "0 -" + radioHeight + "px";
}
},
check: function() {
element = this.nextSibling;
if(element.checked == true && element.type == "checkbox") {
this.style.backgroundPosition = "0 0";
element.checked = false;
} else {
if(element.type == "checkbox") {
this.style.backgroundPosition = "0 -" + checkboxHeight*2 + "px";
} else {
this.style.backgroundPosition = "0 -" + radioHeight*2 + "px";
group = this.nextSibling.name;
inputs = document.getElementsByTagName("input");
for(a = 0; a < inputs.length; a++) {
if(inputs[a].name == group && inputs[a] != this.nextSibling) {
inputs[a].previousSibling.style.backgroundPosition = "0 0";
}
}
}
element.checked = true;
}
},
clear: function() {
inputs = document.getElementsByTagName("input");
for(var b = 0; b < inputs.length; b++) {
if(inputs[b].type == "checkbox" && inputs[b].checked == true && inputs[b].className == "styled") {
inputs[b].previousSibling.style.backgroundPosition = "0 -" + checkboxHeight*2 + "px";
} else if(inputs[b].type == "checkbox" && inputs[b].className == "styled") {
inputs[b].previousSibling.style.backgroundPosition = "0 0";
} else if(inputs[b].type == "radio" && inputs[b].checked == true && inputs[b].className == "styled") {
inputs[b].previousSibling.style.backgroundPosition = "0 -" + radioHeight*2 + "px";
} else if(inputs[b].type == "radio" && inputs[b].className == "styled") {
inputs[b].previousSibling.style.backgroundPosition = "0 0";
}
}
},
choose: function() {
option = this.getElementsByTagName("option");
for(d = 0; d < option.length; d++) {
if(option[d].selected == true) {
document.getElementById("select" + this.name).childNodes[0].nodeValue = option[d].childNodes[0].nodeValue;
}
}
}
}
window.onload = Custom.init;
答案 0 :(得分：1)
抱歉，我的jquery有点生疏（即不存在），但是使用javascript，你可以这样做：
var e = document.getElementById("name");
if (e.options[e.selectedIndex].value == 1) {
e.className = "styled";
}