分享50个使你成为高级javascript开发者的jQuery的代码开发技巧 - 第二部分

转自
http://www.gbin1.com/technology/jquery/50jquerycodesnippetsforbetterjavascript2/index.html

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]);
        }
    });
});
<INPUT class=swap value="Enter Username here.." type=text>
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? 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? 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;
});
<UL>
<LI><A href="#">GBin1 Link 1</A></LI>
<LI><A href="#">GBin1 Link 2</A></LI>
<LI><A href="#">GBin1 Link 3</A></LI>
<LI><A href="#">GBin1 Link 4</A></LI>
</UL>
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*@)?(S+)(:[0-9]+)?(/|/([w#!:.?+=&amp;%@!-/]))?)/gi;
        this.each(function() {
            $(this).html(
                $(this).html().replace(regexp,'<A href="$1">$1</A>')
            );
        });
        return $(this);
    }
//usage
$('#GBin1div').replaceUrl();
原文出处：
分享50个使你成为高级javascript开发者的jQuery的代码开发技巧 - 第一部分
分享50个使你成为高级javascript开发者的jQuery的代码开发技巧 - 第二部分