How to select first child with jQuery?

问题

How do I select the first div in these divs (the one with id=div1) using first child selectors?

<div class=\"alldivs\">
   <div class=\"onediv\" id=\"div1\">
   </div>
   <div class=\"onediv\" id=\"div2\">
   </div>
   <div class=\"onediv\" id=\"div3\">
   </div>
</div>

回答1:

Try with: $('.onediv').eq(0)

demo jsBin

From the demo: Other examples of selectors and methods targeting the first LI unside an UL:

.eq() Method: $('li').eq(0)
:eq() selector: $('li:eq(0)')
.first() Method $('li').first()
:first selector: $('li:first')
:first-child selector: $('li:first-child')
:lt() selector:$('li:lt(1)')
:nth-child() selector:$('li:nth-child(1)')

jQ + JS:

Array.slice() Method: $('li').slice(0,1)

you can also use [i] to get the JS HTMLelement index out of the jQuery el. (array) collection like eg:

$('li')[0]

now that you have the JS element representation you have to use JS native methods eg:

$('li')[0].className = 'active'; // Adds class "active" to the first LI in the DOM

or you can (don't - it's bad design) wrap it back into a jQuery object

$( $('li')[0] ).addClass('active'); // Don't. Use .eq() instead

回答2:

$('div.alldivs :first-child');

Or you can just refer to the id directly:

$('#div1');

As suggested, you might be better of using the child selector:

$('div.alldivs > div:first-child')

If you dont have to use first-child, you could use :first as also suggested, or $('div.alldivs').children(0).

回答3:

Use the :first-child selector.

In your example...

$('div.alldivs div:first-child')

This will also match any first child descendents that meet the selection criteria.

While :first matches only a single element, the :first-child selector can match more than one: one for each parent. This is equivalent to :nth-child(1).

For the first matched only, use the :first selector.

Alternatively, Felix Kling suggested using the direct descendent selector to get only direct children...

$('div.alldivs > div:first-child')

回答4:

As @Roko mentioned you can do this in multiple ways.

1.Using the jQuery first-child selector - SnoopCode

   $(document).ready(function(){
    $(".alldivs onediv:first-child").css("background-color","yellow");
        }

Using jQuery eq Selector - SnoopCode

 $( "body" ).find( "onediv" ).eq(1).addClass( "red" );

Using jQuery Id Selector - SnoopCode

   $(document).ready(function(){
     $("#div1").css("background-color: red;");
   });

回答5:

Hi we can use default method "first" in jQuery

Here some examples:

When you want to add class for first div

  $('.alldivs div').first().addClass('active');

When you want to change the remove the "onediv" class and add only to first child

   $('.alldivs div').removeClass('onediv').first().addClass('onediv');

来源：https://stackoverflow.com/questions/5852452/how-to-select-first-child-with-jquery

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javascript

jquery

children