jquery if div id has children

问题

This if-condition is what's giving me trouble:

if (div id=myfav has children) {
   do something
} else {
   do something else 
}

I tried all the following:

if ( $('#myfav:hasChildren') ) { do something }
if ( $('#myfav').children() ) { do something }
if ( $('#myfav:empty') ) { do something }
if ( $('#myfav:not(:has(*))') ) { do something }

回答1:

if ( $('#myfav').children().length > 0 ) {
     // do something
}

This should work. The children() function returns a JQuery object that contains the children. So you just need to check the size and see if it has at least one child.

回答2:

This snippet will determine if the element has children using the :parent selector:

if ($('#myfav').is(':parent')) {
    // do something
}

Note that :parent also considers an element with one or more text nodes to be a parent.

Thus the div elements in <div>some text</div> and <div><span>some text</span></div> will each be considered a parent but <div></div> is not a parent.

回答3:

Another option, just for the heck of it would be:

if ( $('#myFav > *').length > 0 ) {
     // do something
}

May actually be the fastest since it strictly uses the Sizzle engine and not necessarily any jQuery, as it were. Could be wrong though. Nevertheless, it works.

回答4:

There's actually quite a simple native method for this:

if( $('#myfav')[0].hasChildNodes() ) { ... }

Note that this also includes simple text nodes, so it will be true for a <div>text</div>.

回答5:

and if you want to check div has a perticular children(say <p> use:

if ($('#myfav').children('p').length > 0) {
     // do something
}

回答6:

You can also check whether div has specific children or not,

if($('#myDiv').has('select').length>0)
{
   // Do something here.
   console.log("you can log here");

}

回答7:

The jQuery way

In jQuery, you can use $('#id').children().length > 0 to test if an element has children.

Demo

var test1 = $('#test');
var test2 = $('#test2');

if(test1.children().length > 0) {
    test1.addClass('success');
} else {
    test1.addClass('failure');
}

if(test2.children().length > 0) {
    test2.addClass('success');
} else {
    test2.addClass('failure');
}

.success {
    background: #9f9;
}

.failure {
    background: #f99;
}

<script src="https://code.jquery.com/jquery-1.12.2.min.js"></script>
<div id="test">
   <span>Children</span>
</div>
<div id="test2">
   No children
</div>

---

The vanilla JS way

If you don't want to use jQuery, you can use document.getElementById('id').children.length > 0 to test if an element has children.

Demo

var test1 = document.getElementById('test');
var test2 = document.getElementById('test2');

if(test1.children.length > 0) {
    test1.classList.add('success');
} else {
    test1.classList.add('failure');
}

if(test2.children.length > 0) {
    test2.classList.add('success');
} else {
    test2.classList.add('failure');
}

.success {
    background: #9f9;
}

.failure {
    background: #f99;
}

<div id="test">
   <span>Children</span>
</div>
<div id="test2">
   No children
</div>

来源：https://stackoverflow.com/questions/1526873/jquery-if-div-id-has-children