Check if Obj is in Array then run code if not

Question

I am trying to check if an object is within an array, I have managed to do this however I am unable to run the code within the blocks. Here is the code snippet:

basket.add = function(item) {
    for(var i = 0; i < this.items.length; i++){
        if(item === this.items[i]){
            basket.items[i].count += 1;
        }else{
            basket.items.push(item);  
        };
    };
    basket.print();
};

When I run the code without the if statement it works fine apart from the fact it push the obj again. When I check and then push the obj if it is not in the array this code does not work.

By "unable to run the code within the blocks." do you mean the count is not incrementing, or are you referring to one of the other code blocks? — PartyLich
– PartyLich, Commented Nov 25, 2014 at 20:23
You shouldn't be using semi-colons to end if blocks and for blocks. — David Sherret
– David Sherret, Commented Nov 25, 2014 at 20:26
What data types are item and this.items, you are using === so it checks to see if variables are equal and the same type before returning result. We need more info — Starmetal
– Starmetal, Commented Nov 25, 2014 at 20:28
They are both existing objects created with the new constructor. — hudsond7
– hudsond7, Commented Nov 25, 2014 at 20:29

Stuart · Accepted Answer · 2014-11-25 20:31:07Z

3

Your current code loops through items, pushing another reference to item to the end of the array each time it finds a value in items that doesn't match item. I don't think this is what you want.

Instead you can use

basket.add = function(item) {
    var i = basket.items.indexOf(item);
    if (i == -1) {
        basket.items.push(item);
    }
    else {
        basket.items[i].count += 1;
    }
};

For users of IE8 and earlier .indexOf won't work, so if that's important you can add this polyfill.

answered Nov 25, 2014 at 20:31

Stuart

9,8771 gold badge24 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Jamiec Over a year ago

well done for for explaining the issue better than me!

Jamiec · Accepted Answer · 2014-11-25 20:29:35Z

1

You're looping over your items trying to determine if the item being added is already in the "basket":

for(var i = 0; i < this.items.length; i++){
    if(item === this.items[i]){
       ....

Im guessing you dont want to add the item once for each item in the array already! So move the adding of a new item outside the loop.

Another problem is that you are checking the length of this.items but then pushing to basket.items - this may be valid but I suspect not.

basket.add = function(item) {
    var foundItem = false;
    for(var i = 0; i < this.items.length; i++){
        if(item === this.items[i]){
            this.items[i].count += 1;
            foundItem = true;
            break;
        }
    };
    if(!foundItem){
         this.items.push(item);
    }
    basket.print();
};

answered Nov 25, 2014 at 20:29

Jamiec

136k15 gold badges141 silver badges202 bronze badges

2 Comments

hudsond7 Over a year ago

This solved the problem. Thank you. Could you explain why it was not working?

hudsond7 Over a year ago

I don't understand why it skipped over pushing it to the array. I will check it now.

Collectives™ on Stack Overflow

Check if Obj is in Array then run code if not

2 Answers 2

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related