如果ID存在于使用angularjs的javascript数组中

Question

Okay, I'm done searching and trying code blocks that don't work. This is what I got.

I'm building an array when I click on an image.

    invoices.addItem = function(id) {
        var itemRef = new Firebase(fbUrl+'/items/'+id);
        itemRef.once("value", function(snapshot) {
            invoices.newInvoiceItems.push({
                'id'    : id,
                'name'  : snapshot.val().name,
                'price' : snapshot.val().prices.sale,
                'qty'   : '1'
            });
        }); 
    }

I want to check to see if the ID passed through when the image is clicked again already exists in the array, if it does increase quantity.

All I'm asking for is a simple way to check if the id exists, if it does return true else return false.

if(id exists)
{
  return true;
}
return false;

How do I get the id exists working!?!?!?!?!?!?!?!

UPDATE

This is everything I have:

invoices.addItem = function(id) {
        if(invoices.checkItem(id))
        {
            var index;
            for (index = 0; index < invoices.newInvoiceItems.length; ++index) {
                if(invoices.newInvoiceItems[index].id === id)
                {
                    var qty = invoices.newInvoiceItems[index].qty;
                    invoices.newInvoiceItems[index].qty = qty++;
                }
                else
                {
                    return false;
                }
            }
        }
        else
        {

            var itemRef = new Firebase(fbUrl+'/items/'+id);
            itemRef.once("value", function(snapshot) {
                invoices.newInvoiceItems.push({
                    'id'    : id,
                    'name'  : snapshot.val().name,
                    'price' : snapshot.val().prices.sale,
                    'qty'   : '1'
                });
            });

        }
    }

    invoices.removeItem = function(index) {
        invoices.newInvoiceItems.splice(index, 1);
    }

    invoices.checkItem = function(id) {
        var index;
        for (index = 0; index < invoices.newInvoiceItems.length; ++index) {
            if(invoices.newInvoiceItems[index].id === id)
            {
                return true;
            }
            else
            {
                return false;
            }
        }
    }

Let's say I have two items Item A and Item B . If I click on Item A it adds it to the array. Then click it again and it won't add it but only increases qty one time. Now if I click on Item B without refreshing the page mind you, it adds it over and over and over again each time I click on Item B.

I've console logged the id getting returned and it is always the same one, even though each item has it's own ID.

Answer 1

You can use Array.prototype.filter to quickly and easily find an item in an array. If the item is found... then you know it exists.

var existingItem = invoices.newInvoiceItems.filter(function(item){
    return item.id === id;
})[0];

if(existingItem ){
    ++existingItem.qty
}else{
    //do your firebase thing...
    var itemRef = new Firebase(fbUrl+'/items/'+id);
    itemRef.once("value", function(snapshot) {
        invoices.newInvoiceItems.push({
            'id'    : id,
            'name'  : snapshot.val().name,
            'price' : snapshot.val().prices.sale,
            'qty'   : 1
        });
    });
}