I have an array that I've created in TypeScript and it has a property that I use as a key. If I have that key, how can I remove an item from it?
15 Answers
Same way as you would in JavaScript.
delete myArray[key];
Note that this sets the element to undefined
.
Better to use the Array.prototype.splice
function:
const index = myArray.indexOf(key, 0);
if (index > -1) {
myArray.splice(index, 1);
}
You can use the splice
method on an array to remove the elements.
for example if you have an array with the name arr
use the following:
arr.splice(2, 1);
so here the element with index 2 will be the starting point and the argument 2 will determine how many elements to be deleted.
If you want to delete the last element of the array named arr
then do this:
arr.splice(arr.length-1, 1);
This will return arr with the last element deleted.
Example:
var arr = ["orange", "mango", "banana", "sugar", "tea"];
arr.splice(arr.length-1, 1)
console.log(arr); // return ["orange", "mango", "banana", "sugar"]
This Worked for me
Your Array :
DummyArray: any = [
{"id": 1, "name": 'A'},
{"id": 2, "name": 'B'},
{"id": 3, "name": 'C'},
{"id": 4, "name": 'D'}]
Function:
remove() {
this.DummyArray = this.DummyArray.filter(item => item !== item);
}
Note: This function deletes all the objects form your array. If you want to delete a specific object from array then use this method:
remove(id) {
this.DummyArray = this.DummyArray.filter(item => item.id !== id);
}
Use this, if you need to remove a given object from an array and you want to be sure of the following:
- the list is not reinitialized
- the array length is properly updated
const objWithIdToRemove;
const objIndex = this.objectsArray.findIndex(obj => obj.id === objWithIdToRemove);
if (objIndex > -1) {
this.objectsArray.splice(objIndex, 1);
}
Answer using TypeScript spread operator (...)
// Your key
const key = 'two';
// Your array
const arr = [
'one',
'two',
'three'
];
// Get either the index or -1
const index = arr.indexOf(key); // returns 0
// Despite a real index, or -1, use spread operator and Array.prototype.slice()
const newArray = (index > -1) ? [
...arr.slice(0, index),
...arr.slice(index + 1)
] : arr;
Multiple options in Typescript/Javascript to remove an element from Array. Splice is the best option as
- It removes inline without mutating/creating a new object
- It properly updates the length of the array (wont leave blank null element)
Below is an example of removing an object based on some field in a object array using Splice function
const persons = [
{
firstName :'John',
lastName :'Michel'
},
{
firstName :'William',
lastName :'Scott'
},
{
firstName :'Amanda',
lastName :'Tailor'
}
]
console.log('Before Deleting :'+JSON.stringify(persons));
console.log('Deleting William:');
persons.splice(persons.findIndex(item => item.firstName === 'William'),1);
console.log('After Deleting William'+JSON.stringify(persons));
You can try to get index or position of list or array first, then use for loop to assign current array to a temp list, filter out unwanted item and store wanted item back to original array
removeItem(index) {
var tempList = this.uploadFile;
this.uploadFile = [];
for (var j = 0; j < tempList.length; j++) {
if (j != index)
this.uploadFile.push(tempList[j]);
}
}