Array will not display data, only getting undefined, undefined

Question

[![enter image description here][1]][1]I have been struggling with F--king arrays and objects and they will not display to browser.

I have used a constructor to build the array and then pushed it to the array inventory. I've been fiddling with this for days and I just don't get it. This keeps stopping me in all my projects, the minute I try to access an array I get undefined All I've ever gotten is Undefined. I really don't understand what i've done wrong.

Welcome to SO. I would recommend checking out minimal reproducible example to learn more about how to minimize the code posted to best assist in receiving assistance. — imvain2
– imvain2, Commented Dec 16, 2022 at 22:23
In JavaScript, arrays are zero-indexed. That means your bounds-check should use i < length instead of i <= length. — Oskar Grosser
– Oskar Grosser, Commented Dec 16, 2022 at 22:35
Can you elaborate on your issue "getting undefined, undefined"? Maybe include an error log? — Oskar Grosser
– Oskar Grosser, Commented Dec 16, 2022 at 22:38

Andrew Parks · Accepted Answer · 2022-12-16 22:25:26Z

2

Your for loop says:

for (var i = 0; i <= inventory.length; i++)

But that will go past the last item in the array, because the last item in the array will have the index inventory.length-1 and not inventory.length.

Instead, do:

for (var i = 0; i < inventory.length; i++)

answered Dec 16, 2022 at 22:25

Andrew Parks

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10 Comments

CTR Over a year ago

I thought <= is equal too or less than ? however it doesnt fix my undefined undefined problem

Andrew Parks Over a year ago

@CTR it is. Which means if you have an array of 3 items, i will have the values 0,1,2,3 during the loop. But it should only have the values 0,1,2 during the loop.

Andrew Parks Over a year ago

@CTR please be specific about what buttons to press in your example in order to recreate the undefined problem

CTR Over a year ago

I have added an image to explain the problem I'm having

Andrew Parks Over a year ago

@CTR I don't see that when I load your code example, as long as the < change is made in the for loop. Do I need to push any buttons to see what you're seeing?

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