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The difference between parent() and parents() in jquery traversal and the detailed explanation of parentsUntil() method

巴扎黑
巴扎黑Original
2017-06-24 09:26:121157browse

This article mainly introduces the difference between parent() and parents() in jquery traversal and the parentsUntil() method. Friends who need it can come and refer to it. I hope it will be helpful to everyone.

.parent(selector) Get the parent element# of each element in the current matching element set. ##, filtered by selector (optional).

.parents(selector) Get the ancestor elements of each element in the current matching element set, filtered by the selector (optional) .

Given a jQuery object representing a collection of DOM elements, the .parents() method allows us to search the DOM tree for ancestor elements of these elements and construct it with matching elements in order from the nearest parent element upwards A new jQuery object.

Elements are returned in order from the nearest parent element outward. .parents() is similar to the .parent() method, except that the latter traverses a single level up the DOM tree.

Both methods can accept optional selector expressions of the same type as the parameters we passed to the $() function. If this selector is applied, elements will be filtered by testing whether they match the selector.

The following is an example

The code is as follows:

<ul class="level-1">
 <li class="item-i">I</li>
 <li class="item-ii">II
  <ul class="level-2">
   <li class="item-a">A</li>
   <li class="item-b">B
    <ul class="level-3">
     <li class="item-1">1</li>
     <li class="item-2">2</li>
     <li class="item-3">3</li>
    </ul>
   </li>
   <li class="item-c">C</li>
  </ul>
 </li>
 <li class="item-iii">III</li>
</ul>

If we start from project A, we can find its ancestor elements

The code is as follows:

$(&#39;li.item-a&#39;).parents().css(&#39;background-color&#39;, &#39;red&#39;);

The result of this call is elements such as level-2 list, item II and level-1 list (all the way up the DOM tree until 07e6e06e0dc95dc83bb70d14dca11cbe) sets a red background. Since we didn't apply a selector expression, the parent element naturally becomes part of the object. If a selector is applied, the element is checked to see if it matches the selector before it is included. Since we didn't apply a selector expression, all ancestor elements are part of the returned jQuery object. If a selector is applied, only matching items within it will be included.

If we start from item A, we can find its parent element:


The code is as follows: 

$(&#39;li.item-a&#39;).parent().css(&#39;background-color&#39;, &#39;red&#39;);

The result of this call is, level-2 list sets red background. Since we didn't apply a selector expression, the parent element naturally becomes part of the object. If a selector is applied, the element is checked to see if it matches the selector before it is included.

Let’s look at an example

The code is as follows:

<body>body
    <p id="one">one
        <p id="two">hello</p>
        <p id="three">three
            <p>p
               <a href="#">tonsh</a>
           </p>
        </p>
     </p>
</body>

Thinking:

The code is as follows: 

$("a").parent()
$("a").parents()
$("a").parents("p:eq(0)")
var id=$("a").parents("p:eq(1)").children("p:eq(0)").html();

Example 3

The code is as follows:

<p id=&#39;p1&#39;>
 <p id=&#39;p2&#39;><p></p></p>
 <p id=&#39;p3&#39; class=&#39;a&#39;><p></p></p>
 <p id=&#39;p4&#39;><p></p></p>
</p>

The code is as follows:

$(&#39;p&#39;).parent()
$(&#39;p&#39;).parent(&#39;.a&#39;)
$(&#39;p&#39;).parent().parent()
$(&#39;p&#39;).parents()
$(&#39;p&#39;).parents(&#39;.a&#39;)

Let’s take a look at the previous projects The example used


The code is as follows:

if(
mysql_num_rows
($query)){
  while($arr=
mysql_fetch_array
($query)){
echo <<<admin
          <tr style="
text-align
:center;">
            <td><input type="checkbox" name="checkbox" value="$arr[id]" /></td>
            <td>$arr[id]</td>
            <td>$arr[log]</td>
            <td>$arr[ip]</td>
            <td>$arr[time]</td>
            <td><form><input type="hidden" name="id" value="$arr[id]" /><span class="del">删除</span><img src="images/del.gif" /></form></td>
          </tr>
admin;
  }//while end;
}else{
  echo "<tr align=center><td colspan=6>暂无登陆日志</td></tr>";
}

jquery related code

The code is as follows:

//删除选中日志$(".delcheckbox").click(function(){    var str=&#39;&#39;;    $(".tab input[name=checkbox]:checked").each(function(){        str+=$(this).val()+&#39;,&#39;;    });    str=str.substring(0,str.length-1);    if(chk_Batch_PKEY(str)){        art.dialog.confirm(&#39;你确认删除选中的日志吗？&#39;,function(){            $.post("myRun/managerlog_del.php",{id:str},function(tips){                if(tips==&#39;ok&#39;){                    art.dialog.through({title:&#39;信息&#39;,icon:&#39;face-smile&#39;,content:&#39;删除成功&#39;,ok:function(){art.dialog.close();location.reload();}});                }else{                    art.dialog.tips(&#39;删除失败&#39;);                }            });            return true;        });    }else{        art.dialog.through({title:&#39;信息&#39;,icon:&#39;face-sad&#39;,content:&#39;请选择删除的日志&#39;,ok:function(){art.dialog.close();}});    }}).addClass("pointer");
//del event$(".del").bind("click",function(event){    var _tmpQuery=$(this);    var id=$("input[name=&#39;id&#39;]",$(this).parents("form:first")).attr("value");    art.dialog.confirm(&#39;你确认删除该日志吗？&#39;,function(){        $.post("myRun/managerlog_del.php",{id:id},function(tips){            if(tips==&#39;ok&#39;){                art.dialog.tips(&#39;成功删除&#39;);                _tmpQuery.parents(&#39;tr:first&#39;).hide();            }else{                art.dialog.tips(tips,5);            }        });        return true;    });});


Involved knowledge points:

var id=$("input[name='id']",$(this).parents("form:first")).attr ("value");

References:
parent(): http://www.w3school.com.cn/jquery/traversing_parent.asp

parents(): http://www.w3school.com.cn/jquery/traversing_parents.asp


parentsUntil() method

Definition: parentsUntil () Gets the ancestor elements of each element in the current set of matching elements, up to (but not including) the element matched by the selector, DOM node, or jQuery object.

In fact, the parentsUntil() method, nextUntil() method, and prevUntil() method have the same principle. The only difference is that nextUntil() is going down, prevUntil() is going up (sibling elements), and parentsUntil() is also going up (finding ancestor elements)

Let’s look at an example:


The code is as follows:

<!DOCTYPE html><html><head>  <script type="text/javascript" src="/jquery/jquery.js"></script></head>
<body><ul class="level-1 yes">  <li class="item-i">I</li>  <li class="item-ii">II    <ul class="level-2 yes">      <li class="item-a">A</li>      <li class="item-b">B        <ul class="level-3">          <li class="item-1">1</li>          <li class="item-2">2</li>          <li class="item-3">3</li>        </ul>      </li>      <li class="item-c">C</li>    </ul>  </li>  <li class="item-iii">III</li></ul>
<script>$("li.item-a").parentsUntil(".level-1").css("background-color", "red");
$("li.item-2").parentsUntil( $("ul.level-1"), ".yes"  )  .css("border", "3px solid blue");</script>
</body>

The result is as follows:

Analysis:

The code is as follows:

$ ("li.item-a").parentsUntil(".level-1").css("background-color", "red");

The code is as follows:

<ul class="level-1 yes"> -->不符合。其实它是符合li.item-a的祖先元素的。但是根据parentsUntil()方法定义，是不包括选择器、DOM节点或jquery对象所匹配的元素的
  <li class="item-i">I</li>-->不符合，这是它祖先元素的同辈元素。并不是li.item-a的祖先元素。
  <li class="item-ii">II  -->符合
    <ul class="level-2 yes"> -->符合
      <li class="item-a">A</li> -->从这开始往上找其祖先元素。
      <li class="item-b">B
        <ul class="level-3">
          <li class="item-1">1</li>
          <li class="item-2">2</li>
          <li class="item-3">3</li>
        </ul>
      </li>
      <li class="item-c">C</li>
    </ul>
  </li>
  <li class="item-iii">III</li>
</ul>

Let’s look at the second statement:

The code is as follows: 

$("li.item-2").parentsUntil( $("ul.level-1"), ".yes"  ).css("border", "3px solid blue");

The code is as follows:

<ul class="level-1 yes">-->是其祖先元素 且又满足选择器表达式".yes"，但是根据parentsUntil()方法定义，是不包括选择器、DOM节点或jquery对象所匹配的元素的
  <li class="item-i">I</li> 不匹配，不是其祖先元素。
  <li class="item-ii">II-->是其祖先元素 不满足
    <ul class="level-2 yes"> -->是其祖先元素 满足选择器表达式".yes" [所以，最终匹配到该节点，得到如上图所示的蓝色边框效果]
      <li class="item-a">A</li>
      <li class="item-b">B -->是其祖先元素
        <ul class="level-3"> -->是其祖先元素
          <li class="item-1">1</li>
          <li class="item-2">2</li> -->从这开始往上找其祖先元素。
          <li class="item-3">3</li>
        </ul>
      </li>
      <li class="item-c">C</li>
    </ul>
  </li>
  <li class="item-iii">III</li>
</ul>


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