javascript开发技巧

1. 创建一个嵌套的过滤器

.filter(":not(:has(.selected))") //去掉所有不包含class为.selected的元素

2. 重用你的元素查询

var allItems = $("div.item");  
var keepList = $("div#container1 div.item"); 
<div>class names: 
$(formToLookAt + " input:checked").each(function() {     keepListkeepList = keepList.filter("." + $(this).attr("name")); });
</div>

3. 使用has()来判断一个元素是否包含特定的class或者元素

//jQuery 1.4.* includes support for the has method. This method will find  
//if a an element contains a certain other element class or whatever it is  
//you are looking for and do anything you want to them. 
$("input"
).has(
".email"
).addClass(
"email_icon"
);

4. 使用jQuery切换样式

//Look for the media-type you wish to switch then set the href to your new style sheet  
$('link[media='screen']').attr('href', 'Alternative.css');  

5. 限制选择的区域

//Where possible, pre-fix your class names with a tag name  
//so that jQuery doesn't have to spend more time searching  
//for the element you're after. Also remember that anything  
//you can do to be more specific about where the element is  
//on your page will cut down on execution/search times  
var in_stock = $('#shopping_cart_items input.is_in_stock');

<ul id="shopping_cart_items">  
<li>  
<input value="Item-X" name="item" class="is_in_stock" type="radio"> Item X</li>  
<li>  
<input value="Item-Y" name="item" class="3-5_days" type="radio"> Item Y</li>  
<li>  
<input value="Item-Z" name="item" class="unknown" type="radio"> Item Z</li>  
</ul> 

6. 如何正确使用ToggleClass

//Toggle class allows you to add or remove a class  
//from an element depending on the presence of that  
//class. Where some developers would use:  
a.hasClass('blueButton') ? a.removeClass('blueButton') : a.addClass('blueButton');  
//toggleClass allows you to easily do this using  
a.toggleClass('blueButton'); 

7. 设置IE指定的功能

if ($.browser.msie) { // Internet Explorer is a sadist. } 

8. 使用jQuery来替换一个元素

$('#thatdiv').replaceWith('fnuh');

9. 验证一个元素是否为空

if ($('#keks').html()) { //Nothing found ;}  

10. 在无序的set中查找一个元素的索引

$("ul > li").click(function () {  
    var index = $(this).prevAll().length;  
});

11. 绑定一个函数到一个事件

$('#foo').bind('click', function() {  
  alert('User clicked on "foo."');  
}); 

12. 添加HTML到一个元素

$(
'#lal'
).append(
'sometext'
);

13. 创建元素时使用对象来定义属性

var e = $("", { href: "#", class: "a-class another-class", title: "..." });

14. 使用过滤器过滤多属性

//This precision-based approached can be useful when you use  
//lots of similar input elements which have different types  
var elements = $('#someid input[type=sometype][value=somevalue]').get(); 

15. 使用jQuery预加载图片

jQuery.preloadImages = function() { for(var i = 0; i').attr('src', arguments[i]); } };  
// Usage $.preloadImages('image1.gif', '/path/to/image2.png', 'some/image3.jpg');   

16. 设置任何匹配一个选择器的事件处理程序

$('button.someClass').live('click', someFunction);
  //Note that in jQuery 1.4.2, the delegate and undelegate options have been
  //introduced to replace live as they offer better support for context
    //For example, in terms of a table where before you would use..
  // .live()
  $("table").each(function(){
    $("td", this).live("hover", function(){
    $(this).toggleClass("hover");
    });
  });
  //Now use..
  $("table").delegate("td", "hover", function(){
  $(this).toggleClass("hover");
});

17. 找到被选择到的选项(option)元素

$('#someElement').find('option:selected');

18. 隐藏包含特定值的元素

$("p.value:contains('thetextvalue')").hide();

19. 自动的滚动到页面特定区域

jQuery.fn.autoscroll = function(selector) {
  $('html,body').animate(
    {scrollTop: $(selector).offset().top},
    500
  );
}
//Then to scroll to the class/area you wish to get to like this:
$('.area_name').autoscroll();

20. 检测各种浏览器

Detect Safari (if( $.browser.safari)),
Detect IE6 and over (if ($.browser.msie && $.browser.version > 6 )),
Detect IE6 and below (if ($.browser.msie && $.browser.version <= 6 )),
Detect FireFox 2 and above (if ($.browser.mozilla && $.browser.version >= '1.8' ))

21. 替换字符串中的单词

var el = $('#id');
el.html(el.html().replace(/word/ig, ''));

22. 关闭右键的菜单

$(document).bind('contextmenu',function(e){ return false; });

23. 定义一个定制的选择器

$.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

if ($('#someDiv').length) {//hooray!!! it exists...}

25. 使用jQuery判断鼠标的左右键点击

$("#someelement").live('click', function(e) {
    if( (!$.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

//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" && 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 > 0 : this.selectionStart != this.selectionEnd;
        return !(this.value.length >= max && (keyCode > 50 || keyCode == 32 || keyCode == 0 || keyCode == 13) && !ob.ctrlKey && !ob.altKey && !hasSelection);
      };
      this.onkeyup = function(){
        if(this.value.length > 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 = /<("[^"]*"|'[^']*'|[^'">])*>/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#!:.?+=&%@!-/]))?)/gi;
        this.each(function() {
            $(this).html(
                $(this).html().replace(regexp,'<A href="$1">$1</A>')
            );
        });
        return $(this);
    }
//usage
$('#GBin1div').replaceUrl();