JQuery: Remove duplicate elements?

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.

Use jQuery method $.unique()

Detail see on http://api.jquery.com/jQuery.unique/

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

$(document).ready(function(){
   $("select").each(function () {
       var selectedItem = $(this).find('option').filter(':selected').text();
       var selectedItemValue = $(this).find('option').filter(':selected').val();
       $(this).children("option").each(function(x){
           if(this.text == selectedItem && $(this).val() != selectedItemValue) {
               $(this).remove();
            }
        });
    }); 
});

@interjay @Georg Fritzsche

Your fix didn't work in my case so I build a different version:

var seen='';
   $('a').each(function(){
        var see=$(this).text();
        if(seen.match(see)){
            $(this).remove();}
        else{
            seen=seen+$(this).text();
        }
    });

Hopes this provides someone else with a valid alternative short fix just in case.