Js/jquery常用

id属性不能有空格

1. js判断checkebox是否被选中

var ischecked = document.getElementById("xxx").checked  //返回false or true

设置选上/不选：document.getElementById("xxx").checked=true/false

Jquery

 判断选上：$('#isAgeSelected').attr('checked') // true//false

选上：

$('.myCheckbox').prop('checked', true) or
$('.myCheckbox').attr('checked', true) or
$(".myCheckBox").checked(true);

不选改为false

2. jquery 判断selecte的值

<select name="selector" id="selector">
<option value="1">Option 1</option>
<option value="2">Option 2</option>
</select>

$('select[name=selector]').val()

选中Option 1

$('select[name=selector]').val("1");

3. 往Array中存入对象,

var regions = new Array();

var ri = new Object();
ri.id = "";
ri.name = "";
regions.push(ri);
<c:forEach items="${regionList.values}" var="region">
ri = new Object();
ri.id = "${region.id}";
ri.name = "${region.name}";
regions.push(ri);
</c:forEach>
window.regions = regions;

取数据则 Object region = regions[index];

var regionId = region.id;

Note: js中嵌入了<c:foreach>不建议这么用。

4. bind 与 unbind

$("#name").bind("click", (function () {
$("#attrib_UNIQUE_ACTV_PURCHASE").attr('checked', true);
}));
$("#description").bind("click", (function () {
$("#attrib_UNIQUE_ACTV_PURCHASE").attr('checked', false);
}));
$("#message").bind("click", (function () {
$("#name").unbind("click");
$("#description").unbind("click");
}));

增加点击后选中/不选中或解绑后点击效果

click为eventType,还有其他的

Mouse Events	Keyboard Events	Form Events	Document/Window Events
click	keypress	submit	load
dblclick	keydown	change	resize
mouseenter	keyup	focus	scroll
mouseleave		blur	unload

5.判断元素是否存在：

How do I test whether an element exists?

Use the .length property of the jQuery collection returned by your selector:

1 2 3 4 5

if ( $( "#myDiv" ).length ) {   $( "#myDiv" ).show();   }

Note that it isn't always necessary to test whether an element exists. The following code will show the element if it exists, and do nothing (with no errors) if it does not:

$( "#myDiv" ).show();

or:

It seems some people are landing here, and simply want to know if an element exists (a little bit different to the original question).

That's as simple as using any of the browser's selecting method, and checking it for a truthy value (generally).

For example, if my element had an id of "find-me", I could simply use...

var elementExists = document.getElementById("find-me");
if (elementExists != null){dosomething}

This is spec'd to either return a reference to the element or null.