What is jquery object access and how to use it

What is jquery object access and how to use it_jquery

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Release： 2016-05-16 15:02:38

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This article follows the previous article on jQuery core functions and introduces how to access jQuery objects.

jquery object access

each(callback)

What is jquery object access and how to use it_jquery

size()

What is jquery object access and how to use it_jquery

length

What is jquery object access and how to use it_jquery

selector

What is jquery object access and how to use it_jquery

context

What is jquery object access and how to use it_jquery

get()

What is jquery object access and how to use it_jquery

get(index)

What is jquery object access and how to use it_jquery

index([subject])

What is jquery object access and how to use it_jquery

Test Case

The following is a way to test the above jQuery object access through code, for reference by friends who don’t understand:

<!DOCTYPE html>
<html>
<head>
  <title>jquery对象访问</title>
  <script type="text/javascript" src="./js/jquery.min.js"></script>
</head>
<body>
<!--
  jquery对象访问之一each(callback)
-->
<div>
  <span>span1</span>
  <span>span2</span>
  <span>span3</span>
  <span>span4</span>
  <span>span5</span>
</div>
<script type="text/javascript">
  var spanList = $("div span");
  spanList.each(function(){
    // alert(this.innerHTML);  //这个获取的是span元素而不是jQuery对象，这点需要注意。依次输出span1 ... span5
    // alert($(this).html()); //输出结果同上 只是$(this)会将元素转为jQuery对象
    if($(this).html() == "span4")
      return false;      //可以提前使用return 退出循环
  });
</script>
<!--
  jquery对象访问之二size()
-->
<script type="text/javascript">
  // alert($("div span").size());  //输出结果5 size()函数是获取jQuery集合中元素的个数
</script>
<!--
  jquery对象访问之三length
-->
<script type="text/javascript">
  // alert($("div span").length);  //输出结果5 当前匹配的元素个数.同size 返回相同的值
</script>
<!--
  jquery对象访问之四selector
-->
<ul id="ul1"></ul>
<script type="text/javascript">
  $("#ul1")
   .append("<li>" + $("ul").selector + "</li>")
   .append("<li>" + $("ul li").selector + "</li>")
   .append("<li>" + $("div#foo ul:not([class])").selector + "</li>");
</script>
<!--
  jquery对象访问之五context
-->
<ul id="ul2"></ul>
<script type="text/javascript">
  $("#ul2")
   .append("<li>" + $("ul").context + "</li>")
   .append("<li>" + $("ul", document.body).context.nodeName + "</li>");
</script>
<!--
  jquery对象访问之六get()
-->
<div id="get">
  <span>get1</span>
  <span>get2</span>
  <span>get3</span>
  <span>get4</span>
</div>
<script type="text/javascript">
  var spans = $("#get span");
  var span1 = spans.get();
  // alert(span1);  // 返回的是span元素的集合
  // alert($(span1).html()); //输出结果get1 将节点元素包装成jQuery对象
</script>
<!--
  jquery对象访问之七get(index)
-->
<div id="get">
  <span>get1</span>
  <span>get2</span>
  <span>get3</span>
  <span>get4</span>
</div>
<script type="text/javascript">
  var spans = $("#get span");
  var span1 = spans.get(0);
  // alert(span1.innerText); //输出结果是get1 通过节点元素
  // alert($(span1).html()); //输出结果同上   将节点元素包装成jQuery对象
</script>
<!--
  jquery对象访问之八index([subject])
-->
<ul id="ul8">
 <li id="foo">foo</li>
 <li id="bar">bar</li>
 <li id="baz">baz</li>
</ul>
<script type="text/javascript">
  alert($('#ul8 li').index(document.getElementById('bar'))); //1，传递一个DOM对象，返回这个对象在原先集合中的索引位置
  alert($('#ul8 li').index($('#bar'))); //1，传递一个jQuery对象
  alert($('#ul8 li').index($('#ul8 li:gt(0)'))); //1，传递一组jQuery对象，返回这个对象中第一个元素在原先集合中的索引位置
  alert($('#bar').index('#ul8 li'));   //1，传递一个选择器，返回#bar在所有li中的做引位置
  alert($('#bar').index()); //1，不传递参数，返回这个元素在同辈中的索引位置。
</script>
</body>
</html>

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What is jquery object access and how to use it_jquery

Summary

This article introduces jQuery’s object access module. I didn't learn jQuery systematically before, but now I plan to learn jQuery systematically and post it for reference by friends who need it. If anything is wrong, please correct me. Thank you everyone for reading!