TypeError: null is not an object (evaluating '*')

Question

For the below code:

var item = cartModel.getlist()[index];
if((item.isDepo()) {
    // Some code
} else if(!permission.hasPermissionToVoidSKU()) {
    // Some code
} else if(item.sku.indexOf(mposConstants.RESTOCK_FEE_SKU) > -1){
                // Some code 
}

I'm getting this error:

TypeError: null is not an object (evaluating 'item.sku.indexOf')

If item object is null, the error is something different (see below). In what scenario will this error be thrown?

Update:

If item.sku is null, the error is:

[FATAL] [] [-] ["TypeError: Cannot read property 'indexOf' of null

If item is null, the error is:

[FATAL] [] [-] ["TypeError: Cannot read property 'isDepo' of null

@freginold I want know in what scenario this error will be thrown — I'm nidhin, Dec 05 '17 at 14:25
you lost the reference then (it was deleted?); the referring function was called before the element was parsed into the DOM — Aleksey Solovey, Dec 05 '17 at 14:39
What errors do you get if `item` or `item.sku` are `undefined` instead of `null`? — freginold, Dec 05 '17 at 14:45
did you double check the value of `mposConstants.RESTOCK_FEE_SKU`? — phuzi, Dec 05 '17 at 14:47

score 12 · Answer 1 · edited May 18 '19 at 01:12

The reason for the different error messages is quite simply that they are produced by different browsers. The error is the same (sku on the object item is null).

Given the following code

<script>
  var item = {sku: null};
  item.sku.indexOf("");
</script>

here is some error messages for different browsers:

Firefox: TypeError: item.sku is null
Firefox Developer Edition: TypeError: item.sku is null, can't access property "indexOf" of it
Opera: TypeError: Cannot read property 'indexOf' of null at example.html:3
Safari: TypeError: null is not an object (evaluating 'item.sku.indexOf')

To get the error message you have gotten, item must be defined as an object, and sku must be set to null. If sku were undefined, you would have gotten an error message like this (Safari): TypeError: undefined is not an object (evaluating 'item.sku.indexOf'). If item was null, you would have gotten something like this: TypeError: null is not an object (evaluating 'item.sku').

score 2 · Answer 2 · answered Dec 05 '17 at 14:55

Based on this answer and others, it sounds like you're getting that error because a function is called before the DOM element it references or acts upon has been loaded.

In the snippet of code you provided, I don't see a direct reference to any DOM elements, but I would suggest calling your script after your HTML has finished rendering (i.e. by putting any <script> tags at the end of your HTML, or by using a $(document).ready() call if you use jQuery).

TypeError: null is not an object (evaluating '*')

2 Answers2