Question

I want to implement some sort of hasObject function with underscore.js.

Example:

var Collection = {
    this.items: [];
    this.hasItem: function(item) {
        return _.find(this.items, function(existingItem) { //returns undefined
            return item % item.name == existingItem.name;
        });
    }
};

Collection.items.push({ name: "dev.pus", account: "stackoverflow" });
Collection.items.push({ name: "margarett", account: "facebook" });
Collection.items.push({ name: "george", account: "google" });

Collection.hasItem({ name: "dev.pus", account: "stackoverflow" }); // I know that the name would already be enough...

For some reason underscores find returns undefined…

What am I doing wrong?

Answer 1

It looks like you are reading underscore documentation too literally, where
they have:

var even = _.find([1, 2, 3, 4, 5, 6], function(num){ return num % 2 == 0; });

However, this doesn’t make any sense for your case, you just want to see if the .name property is equal to
some other object’s .name, like this:

var Collection = {
    items: [],

    hasItem: function(item) {
        return _.find(this.items, function(existingItem) { //returns undefined
            return item.name === existingItem.name;
        });
    }
};