获取jquery中元素的第n个子编号

Question

I have a class of multiple 'DIV' elements and inside it are list of 'p' elements. See below:

<div class="container">
    <p>This is content 1</p>
    <p>This is content 2</p>
    <p>This is content 3</p>
</div>
<div class="container">
    <p>This is content 1</p>
    <p>This is content 2</p>
    <p>This is content 3</p>
</div>

Here's my jQuery code on calling the 'p' elements through hover:

$('.container').children('p').hover(function(){
    //get the nth child of p from parent class 'container'
});

How can I get the nth child number of the element 'p' from its parent container class 'container'?

Like if you hover

This is content 1

it should trigger output as 1;

Answer 1

You can use jQuery's index function for that. It tells you where the given element is relative to its siblings:

var index = $(this).index();

Live example | source

The indexes are 0-based, so if you're looking for a 1-based index (eg, where the first one is 1 rather than 0 ), just add one to it:

var index = $(this).index() + 1;

---

If you're not using jQuery and came across this question and answer (the OP was using jQuery), this is also quite simple to do without it. nth-child only considers elements , so:

function findChildIndex(node) {
    var index = 1;                         // nth-child starts with 1 = first child
    // (You could argue that you should throw an exception here if the
    // `node` passed in is not an element [e.g., is a text node etc.]
    // or null.)
    while (node.previousSibling) {
        node = node.previousSibling;
        if (node && node.nodeType === 1) { // 1 = element
            ++index;
        }
    }
    return index;
}

Answer 2

Use the parameter-less version of the .index() method to find the position of the element relative to its siblings:

$('.container').children('p').hover(function() {
     var index = $(this).index() + 1;
});

Note that the result of .index() will be zero-based, not one-based, hence the + 1

Answer 3

$('.container').children('p').hover(function(){
    //get the nth child of p from parent class 'container'
    var n = 1;
    var child = $(this).parent().find("p:eq("+n+")");
});

Should work!

Or if you want to know the index of the hovered element:

$('.container').children('p').each(function(index,element) {
    // use closure to retain index
    $(element).hover(function(index){
        return function() { alert(index); }
    }(index);
}

See http://api.jquery.com/each/