Jquery array: Prevent duplicates insert

Question

Based on a post I've seen. I am creating a temporary array elements by clicking on a hyperlink. The only problem I have is that it can generate repeated elements, which until now have not been resolved:

var items = new Array();
$("ul.dropdown li a").click(function(e)
{
    e.preventDefault();

    var id      = $(this).attr('href');
    var name    = $(this).text();

    if(!$.findFromArray('id', id, items))
    {
        return false;       
    }
    else
    {
        items.push({
            "id"    : id,
            "name": name
        });

        //genate row
        var newRow = $("<tr itemId=\"" + id  + "\" />")
        .appendTo(".form_list.left tbody")
        .append("<td>" + name + "</td>")
        .append("<td><a href=\"#\" class=\"deleteRow\">delete</a></td>");


        $(".deleteRow", newRow).click(function(e) {
                e.preventDefault();
                items = $.removeFromArray('id', $(this).closest("tr").attr("itemId"), items);
                $(this).closest("tr").remove(); 
        });     
    }
});

I created a function "$.FindFromArray" that searches the array the insert and returns FALSE if there is to avoid inserting in the array and generate a line in the table:

$.findFromArray = function(property, value, arr)
{
    $.each(arr, function(elem, index)
    {
        if(elem[property] === value)
        {
            return false;           
        }   
    }); 
};

But this function always returns me FALSE.

As I can avoid duplication before inserting the element? if a better way to do it ... I hope I can help.

Try using $.inArray(); -> api.jquery.com/jQuery.inArray

benqus
– benqus

2012-05-19 13:47:06 +00:00
Commented May 19, 2012 at 13:47 — benqus
– benqus, Commented May 19, 2012 at 13:47

Gabriele Petrioli · Accepted Answer · 2012-05-19 14:03:31Z

3

Change you method to

$.findFromArray = function(property, value, arr)
{
    var matching = $(arr).filter(function(index, elem)
    {
        return elem[property] === value;
    }); 
    return matching.length > 0;
};

this returns true if it found the element in the array (makes it more readable this way), so you should also alter the check to

if( $.findFromArray('id', id, items) )

removed the !

edited May 19, 2012 at 14:03

answered May 19, 2012 at 13:47

Gabriele Petrioli

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3 Comments

csotelo Over a year ago

But I always returns TRUE, FALSE should be returned when the item already exists in the array

Gabriele Petrioli Over a year ago

@csotelo, nope. The method I posted returns true if the element exists in the array or false if it does not. If you want to invert the result change the last line to return matching.length === 0

csotelo Over a year ago

Oops sorry! I put the function in an alert ... but change the if statement and now it works great! thank you!

adeneo · Accepted Answer · 2012-05-19 14:07:51Z

1

You've mixed up the order of index and element in $.each, and you only return from inside the $.each function, not the $.findFromArray function :

$.findFromArray = function(property, value, arr)
    var ret=false;
    $.each(arr, function(index, elem) {
        if (elem[property] === value) ret=true;
    }); 
    return ret;
};

answered May 19, 2012 at 14:07

adeneo

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