JQuery selectors for first li

问题

I need an onclick event, when the user clicks on the first li aka(Any Date).How do I select that element using jQuery?

<ul id="ui-id-1" class="ui-menu ui-widget ui-widget-content" role="menu" tabindex="0" aria-activedescendant="ui-id-5">
   <li class="ui-menu-item" id="ui-id-2" tabindex="-1" role="menuitem">
    <a href="#">Any Date</a></li>
   <li class="ui-menu-item" id="ui-id-3" tabindex="-1" role="menuitem">
    <a href="#">Past 7 days</a></li>
   <li class="ui-menu-item" id="ui-id-4" tabindex="-1" role="menuitem">
    <a href="#">Past month</a></li>
   <li class="ui-menu-item" id="ui-id-5" tabindex="-1" role="menuitem">
    <a href="#">Past year</a></li>
</ul>

回答1:

You can use jquery :first selector to target the 1st element in a collection of elements.

$('ul li:first').click(function()
{
   // do something 
});

Example : https://jsfiddle.net/3mb8ep19/

or jquery first() filter :

$('ul li').first().click(function()
{
   // do something
});

Example : https://jsfiddle.net/3mb8ep19/1/

回答2:

Well it has an id so you can use that in your selector. You are targeting the link inside the li correct?

$("#ui-id-2 a").click(function(){
 // function goes here

 return false; // the link itself has a behaviour associated with it so we want to stop that
});

Otherwise for something more generic you can use the :first-child selector.

Note : While :first matches only a single element, the :first-child selector can match more than one: one for each parent.

$("ul.ui-menu li:first-child a").click(function(){});

回答3:

You can use :first-child

$("ul.ui-menu li.ui-menu-item:first-child").on("click", function() {
  $(this).css("background", "red");
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul id="ui-id-1" class="ui-menu ui-widget ui-widget-content" role="menu" tabindex="0" aria-activedescendant="ui-id-5">
  <li class="ui-menu-item" id="ui-id-2" tabindex="-1" role="menuitem">
    <a href="#">Any Date</a>
  </li>
  <li class="ui-menu-item" id="ui-id-3" tabindex="-1" role="menuitem">
    <a href="#">Past 7 days</a>
  </li>
  <li class="ui-menu-item" id="ui-id-4" tabindex="-1" role="menuitem">
    <a href="#">Past month</a>
  </li>
  <li class="ui-menu-item" id="ui-id-5" tabindex="-1" role="menuitem">
    <a href="#">Past year</a>
  </li>
</ul>

回答4:

You can use any of the methods given below to select first li element.

1. using jQuery :nth-child selector It selects the child of the element using its position. The value 1 select the li item located at first position.

$( "ul li:nth-child(1)" ).click(function(){
		//do something here
	});

2. using jQuery :first selector It selects the first li item.

$( "ul li:first" ).click(function(){
		//do something here
	});

3. using jQuery :eq() selector The li element starts with index 0. To select first item, you have use 0 as its value.

$( "ul li:eq(0)" ).click(function(){
		//do something here
	});

See this: Get the First Element of li Using jquery for live examples.

来源：https://stackoverflow.com/questions/36048421/jquery-selectors-for-first-li

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