JQuery: Remove duplicate elements?

Question

Say I have a list of links with duplicate values as below:

<a href="#">Book</a>
<a href="#">Magazine</a>
<a href="#">Book</a>
<a href="#">Book</a>
<a href="#">DVD</a>
<a href="#">DVD</a>
<a href="#">DVD</a>
<a href="#">Book</a>

How would I, using JQuery, remove the dups and be left with the following for example:

<a href="#">Book</a>
<a href="#">Magazine</a>
<a href="#">DVD</a>

Basically I am looking for a way to remove any duplicate values found and show 1 of each link.

Answer 1

var seen = {};
$('a').each(function() {
    var txt = $(this).text();
    if (seen[txt])
        $(this).remove();
    else
        seen[txt] = true;
});

Explanation:

seen is an object which maps any previously seen text to true. It functions as a set containing all previously seen texts. The line if (seen[txt]) checks to see if the text is in the set. If so, we've seen this text before, so we remove the link. Otherwise, this is a link text we see for the first time. We add it to the set so that any further links with the same text will be removed.

An alternative way to represent a set is to use an array containing all values. However, this would make it much slower since to see if a value is in the array we'd need to scan the entire array each time. Looking up a key in an object using seen[txt] is very fast in comparison.

Answer 2

// use an object as map
var map = {};
$("a").each(function(){
    var value = $(this).text();
    if (map[value] == null){
        map[value] = true;
    } else {
        $(this).remove();
    }
});

Answer 3

A quick and easy way would be

$("a").​​​​​​​​each(function(){
    if($(this).parent().length)
        $("a:contains('" + $(this).html() + "')").not(this).remove();
});​