60个很实用的jQuery代码开发技巧收集

26. 显示或者删除输入框的缺省值

//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 class=swap 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）

//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

var newgbin1Div = $('');
newgbin1Div.attr('id','gbin1.com').appendTo('body');

29. 限制textarea的字符数量

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" amp;amp; 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 amp;amp; (keyCode gt; 50 || keyCode == 32 || keyCode == 0 || keyCode == 13) amp;amp; !ob.ctrlKey amp;amp; !ob.altKey amp;amp; !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

//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" );
});

31. 使用jQuery克隆元素

var cloned = $('#gbin1div').clone();

32. 测试一个元素在jQuery中是否可见

if($(element).is(':visible') == 'true') { //The element is Visible }

33. 元素屏幕居中

jQuery.fn.center = function () {
 this.css('position','absolute');
 this.css('top', ( $(window).height() - this.height() ) / +$(window).scrollTop() + 'px');
 this.css('left', ( $(window).width() - this.width() ) / 2+$(window).scrollLeft() + 'px');return this;
}
//Use the above function as: $('#gbin1div').center();

34. 使用特定名字的元素对应的值生成一个数组

var arrInputValues = new Array();
$("input[name='table[]']").each(function(){
  arrInputValues.push($(this).val());
});

35. 剔除元素中的HTML

(function($) {
 $.fn.stripHtml = function() {
  var regexp = /lt;("[^"]*"|'[^']*'|[^'"gt;])*gt;/gi;
  this.each(function() {
   $(this).html(
    $(this).html().replace(regexp,"")
   );
  });
  return $(this);
 }
})(jQuery);
//usage:
$('p').stripHtml();

36. 使用closest来得到父元素

$('#searchBox').closest('div');

37. 使用firebug来记录jQuery事件

// Allows chainable logging
// Usage: $('#someDiv').hide().log('div hidden').addClass('someClass');
jQuery.log = jQuery.fn.log = function (msg) {
  if (console){
   console.log("%s: %o", msg, this);
  }
  return this;
};

38. 点击链接强制弹出新窗口

jQuery('a.popup').live('click', function(){
 newwindow=window.open($(this).attr('href'),'','height=200,width=150');
 if (window.focus) {newwindow.focus()}
 return false;
});

39. 点击链接强制打开新标签页

jQuery('a.newTab').live('click', function(){
 newwindow=window.open($(this).href);
 jQuery(this).target = "_blank";
 return false;
});

40. 使用siblings()来处理同类元素

// Rather than doing this
$('#nav li').click(function(){
 $('#nav li').removeClass('active');
 $(this).addClass('active');
});
// Do this instead
$('#nav li').click(function(){
 $(this).addClass('active')
  .siblings().removeClass('active');
});

41. 选择或者不选页面上全部复选框

var tog = false; // or true if they are checked on load
$('a').click(function() {
 $("input[type=checkbox]").attr("checked",!tog);
 tog = !tog;
});

42. 基于输入文字过滤页面元素

//If the value of the element matches that of the entered text
//it will be returned
$('.gbin1Class').filter(function() {
 return $(this).attr('value') == $('input#gbin1Id').val() ;
 })

43. 取得鼠标的X和Y坐标

$(document).mousemove(function(e){
$(document).ready(function() {
$().mousemove(function(e){
$('#XY').html("Gbin1 X Axis : " + e.pageX + " | Gbin1 Y Axis " + e.pageY);
});
});

44. 使得整个列表元素(LI)可点击

$("ul li").click(function(){
 window.location=$(this).find("a").attr("href"); return false;
});

lt;ULgt;
lt;LIgt;lt;A href="#"gt;GBin1 Link 1lt;/Agt;lt;/LIgt;
lt;LIgt;lt;A href="#"gt;GBin1 Link 2lt;/Agt;lt;/LIgt;
lt;LIgt;lt;A href="#"gt;GBin1 Link 3lt;/Agt;lt;/LIgt;
lt;LIgt;lt;A href="#"gt;GBin1 Link 4lt;/Agt;lt;/LIgt;
lt;/ULgt; 

45. 使用jQuery来解析XML

function parseXml(xml) {
 //find every Tutorial and print the author
 $(xml).find("Tutorial").each(function()
 {
 $("#output").append($(this).attr("author") + "");
 });
}

46. 判断一个图片是否加载完全

$('#theGBin1Image').attr('src', 'image.jpg').load(function() {
alert('This Image Has Been Loaded');
});

47. 使用jQuery命名事件

//Events can be namespaced like this
$('input').bind('blur.validation', function(e){
 // ...
});
//The data method also accept namespaces
$('input').data('validation.isValid', true);

48. 判断cookie是否激活或者关闭

var dt = new Date();
dt.setSeconds(dt.getSeconds() + 60);
document.cookie = "cookietest=1; expires=" + dt.toGMTString();
var cookiesEnabled = document.cookie.indexOf("cookietest=") != -1;
if(!cookiesEnabled)
{
 //cookies have not been enabled
}

49. 强制过期cookie

var date = new Date();
date.setTime(date.getTime() + (x * 60 * 1000));
$.cookie('example', 'foo', { expires: date });

50. 使用一个可点击的链接替换页面中所有URL

$.fn.replaceUrl = function() {
  var regexp = /((ftp|http|https)://(w+:{0,1}w*@)#63;(S+)(:[0-9]+)#63;(/|/([w#!:.#63;+=amp;%@!-/]))#63;)/gi;
  this.each(function() {
   $(this).html(
    $(this).html().replace(regexp,'lt;A href="$1"gt;$1lt;/Agt;')
   );
  });
  return $(this);
 }
//usage
$('#GBin1div').replaceUrl(); 

51: 在表单中禁用“回车键”

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