16. 验证元素是否存在于Ｊｑｕｅｒｙ对象集合中view plaincopy to clipboardprint?

1. $(document).ready(function() {

2. if ($('#id').length) {

3. // do something

4.   }

5. });

17. 使整个ＤＩＶ可点击view plaincopy to clipboardprint?

1. $(document).ready(function() {

2.     $("div").click(function(){

3. //get the url from href attribute and launch the url

4.       window.location=$(this).find("a").attr("href"); return false;

5.     });

6. // how to use

7. <DIV><A href="index.html">home</A></DIV>

8.

9. });

18.ID与Class之间转换当改变Window大小时，在ID与Class之间切换

view plaincopy to clipboardprint?

1. $(document).ready(function() {

2. function checkWindowSize() {

3. if ( $(window).width() > 1200 ) {

4.         $('body').addClass('large');

5.     }

6. else {

7.         $('body').removeClass('large');

8.     }

9.    }

10. $(window).resize(checkWindowSize);

11. });

19. 克隆对象view plaincopy to clipboardprint?

1. $(document).ready(function() {

2. var cloned = $('#id').clone();

3. // how to use

4. <DIV id=id></DIV>

5.

6. });

20. 使元素居屏幕中间位置view plaincopy to clipboardprint?

1. $(document).ready(function() {

2.   jQuery.fn.center = function () {

3. this.css("position","absolute");

4. this.css("top", ( $(window).height() - this.height() ) / 2+$(window).scrollTop() + "px");

5. this.css("left", ( $(window).width() - this.width() ) / 2+$(window).scrollLeft() + "px");

6. return this;

7.   }

8.   $("#id").center();

9. });

21. 写自己的选择器view plaincopy to clipboardprint?

1. $(document).ready(function() {

2.    $.extend($.expr[':'], {

3.        moreThen1000px: function(a) {

4. return $(a).width() > 1000;

5.       }

6.    });

7.   $('.box:moreThen1000px').click(function() {

8. // creating a simple js alert box

9.       alert('The element that you have clicked is over 1000 pixels wide');

10.   });

11. });