Encountering an undefined error when trying to remove an object from an array using Angular

Question

Encountering an undefined error when trying to remove an object from an array using Angular

I currently have an array of objects representing items. These items are fetched from a service and displayed on the cart page.

When I click on the remove button, I execute the delete this.cart.items[i]; function. The item is successfully removed from the service object, but a blank element appears on the page along with console errors stating

Cannot read property 'qty' of undefined

. I assumed that ngfor would automatically update the DOM to remove the element when the object is deleted. Do I need to manually remove the element from the DOM as well?

In the example array provided below, my goal is to completely remove the first item while still displaying the second item.

[
  {
    "desc": "Description",
    "item": "item 1",
    "id": "1",
    "portion": "small",
    "price": "4.25",
    "qty": 3
  },
  {
    "desc": "Description",
    "item": "item 2",
    "id": "2",
    "portion": "large",
    "price": "4",
    "qty": 1
  }
]


<div class="cart-item" *ngFor="let item of items" (click)='ontap(item);'>
    {{ x.item }}
</div>

This is where I am displaying the items, however the element with no data is still visible. Any suggestions on how to resolve this issue would be appreciated. Thank you.

angular typescript ngfor

Answer 1

Answer №1

To access the index on your button click, you can utilize the ngFor directive:

<div class="cart-item" *ngFor="let item of items; let i = index" (click)='onRemove(i);'>
    {{ x.item }}
</div>

You can then use this index to remove an item from the array and update the array accordingly:

onRemove(index: number) {
   this.items = [...this.items.splice(index, 1)]
}

Please note: The spread operator is employed to trigger change detection in Angular.

Answer 2

To access the index on your button click, you can utilize the ngFor directive:

<div class="cart-item" *ngFor="let item of items; let i = index" (click)='onRemove(i);'>
    {{ x.item }}
</div>

You can then use this index to remove an item from the array and update the array accordingly:

onRemove(index: number) {
   this.items = [...this.items.splice(index, 1)]
}

Please note: The spread operator is employed to trigger change detection in Angular.

Answer 3

Answer №2

The method this.cart.items.splice(i,1) should be used to correctly remove an element from an array. When using the delete statement, the item is removed but the length of the array remains the same.

this.cart.items.splice(i,1);

Answer 4

The method this.cart.items.splice(i,1) should be used to correctly remove an element from an array. When using the delete statement, the item is removed but the length of the array remains the same.

this.cart.items.splice(i,1);

Answer 5

Answer №3

When utilizing the onPush strategy with your simple component, the value in the DOM will not automatically update.

To ensure that the view updates accordingly, you must follow this pattern:

let updatedItems = this.list.items.splice(index, 1);

this.list = {
...this.list,
items: updatedItems
}

By implementing this structure, any changes to the Input will be reflected in the view.

Furthermore, remember that removing an item from an array should be done using the splice method.

Answer 6

When utilizing the onPush strategy with your simple component, the value in the DOM will not automatically update.

To ensure that the view updates accordingly, you must follow this pattern:

let updatedItems = this.list.items.splice(index, 1);

this.list = {
...this.list,
items: updatedItems
}

By implementing this structure, any changes to the Input will be reflected in the view.

Furthermore, remember that removing an item from an array should be done using the splice method.

Encountering an undefined error when trying to remove an object from an array using Angular

Answer №1

Answer №2

Answer №3

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