30个经典的jQuery代码开发技巧

23. 定义一个定制的选择器
复制代码 代码如下:$.expr[':'].mycustomselector = function(element, index, meta, stack){
// element- is a DOM element
// index - the current loop index in stack
// meta - meta data about your selector
// stack - stack of all elements to loop
// Return true to include current element
// Return false to explude current element
};
// Custom Selector usage:
$('.someClasses:test').doSomething();

24. 判断一个元素是否存在
复制代码 代码如下:if ($('#someDiv').length) {
//hooray!!! it exists...
}

25. 使用jQuery判断鼠标的左右键点击
复制代码 代码如下:$("#someelement").live('click', function(e) { if( (!$.browser.msie e.button == 0) || ($.browser.msie e.button == 1) ) { alert("Left Mouse Button Clicked"); } else if(e.button == 2) alert("Right Mouse Button Clicked"); });

26. 显示或者删除输入框的缺省值
复制代码 代码如下://This snippet will show you how to keep a default value
//in a text input field for when a user hasn't entered in
//a value to replace it
swap_val = [];
$(".swap").each(function(i){ swap_val[i] = $(this).val();
$(this).focusin(function(){ if ($(this).val() == swap_val[i]) { $(this).val(""); } }).focusout(function(){ if ($.trim($(this).val()) == "") { $(this).val(swap_val[i]); } }); }); lt;INPUT value="Enter Username here.." type=textgt;

27. 指定时间后自动隐藏或者关闭元素(1.4支持）
复制代码 代码如下://Here's how we used to do it in 1.3.2 using setTimeout
setTimeout(function() { $('.mydiv').hide('blind', {}, 500) }, 5000);
//And here's how you can do it with 1.4 using the delay() feature (this is a lot like sleep)
$(".mydiv").delay(5000).hide('blind', {}, 500);

28. 动态创建元素到DOM
复制代码 代码如下:var newgbin1Div = $('');
newgbin1Div.attr('id','gbin1.com').appendTo('body');

29. 限制textarea的字符数量
复制代码 代码如下:jQuery.fn.maxLength = function(max){ this.each(function(){ var type = this.tagName.toLowerCase();
var inputType = this.type#63; this.type.toLowerCase() : null; if(type == "input"
inputType == "text" || inputType == "password"){
//Apply the standard maxLength this.maxLength = max;
} else if(type == "textarea"){ this.onkeypress = function(e){ var ob = e || event;
var keyCode = ob.keyCode;
var hasSelection = document.selection#63; document.selection.createRange().text.length gt; 0 : this.selectionStart != this.selectionEnd;
return !(this.value.length gt;= max
(keyCode gt; 50 || keyCode == 32 || keyCode == 0 || keyCode == 13) !ob.ctrlKey !ob.altKey !hasSelection); };
this.onkeyup = function(){ if(this.value.length gt; max){ this.value = this.value.substring(0,max); } }; } }); };
//Usage:
$('#gbin1textarea').maxLength(500);

30. 为函数创建一个基本测试用例
复制代码 代码如下://Separate tests into modules.
module("Module B");
test("some other gbin1.com test", function() {
//Specify how many assertions are expected to run within a test. expect(2); //A comparison assertion, equivalent to JUnit's assertEquals.
equals( true, false, "failing test" );
equals( true, true, "passing test" );
});

希望本文所述对大家的jquery程序设计有所帮助。

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