How do I remove an array item in TypeScript?
ArraysTypescriptCollectionsArrays Problem Overview
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?
Arrays Solutions
Solution 1 - Arrays
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);
}
Solution 2 - Arrays
let foo_object; // Itemitem(object here) to remove
this.foo_objects = this.foo_objects.filter(obj => return obj !== foo_object);
Solution 3 - Arrays
With ES6 you can use this code :
removeDocument(doc){
this.documents.forEach( (item, index) => {
if(item === doc) this.documents.splice(index,1);
});
}
Solution 4 - Arrays
It is my solution for that:
onDelete(id: number) {
this.service.delete(id).then(() => {
let index = this.documents.findIndex(d => d.id === id); //find index in your array
this.documents.splice(index, 1);//remove element from array
});
event.stopPropagation();
}
Solution 5 - Arrays
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"]
Solution 6 - Arrays
let departments is an array. You want to remove an item from this array.
departments: string[] = [];
removeDepartment(name: string): void {
this.departments = this.departments.filter(item => item != name);
}
Solution 7 - Arrays
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);
}
Solution 8 - Arrays
Here's a simple one liner for removing an object by property from an array of objects.
delete this.items[this.items.findIndex(item => item.item_id == item_id)];
or
this.items = this.items.filter(item => item.item_id !== item.item_id);
Solution 9 - Arrays
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);
}
Solution 10 - Arrays
Multiple options in Typescript/Javascript to remove an element from Array. Splice is the best option as
- It removes inline without 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));
Solution 11 - Arrays
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;
Solution 12 - Arrays
One more solution using Typescript:
let updatedArray = [];
for (let el of this.oldArray) {
if (el !== elementToRemove) {
updated.push(el);
}
}
this.oldArray = updated;
Solution 13 - Arrays
let a: number[] = [];
a.push(1);
a.push(2);
a.push(3);
let index: number = a.findIndex(a => a === 1);
if (index != -1) {
a.splice(index, 1);
}
console.log(a);
Solution 14 - Arrays
Just wanted to add extension method for an array.
interface Array<T> {
remove(element: T): Array<T>;
}
Array.prototype.remove = function (element) {
const index = this.indexOf(element, 0);
if (index > -1) {
return this.splice(index, 1);
}
return this;
};
Solution 15 - Arrays
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]);
}
}
Solution 16 - Arrays
We can implement the logic using filter
and includes
const checkAlpha2Code = ['BD', 'NZ', 'IN']
let countryAlpha2Code = ['US', 'CA', 'BD', 'NZ', 'AF' , 'AR' , 'BR']
/**
* Returns the modified array countryAlpha2Code
* after removing elements which matches with the checkAlpha2Code
*/
countryAlpha2Code = countryAlpha2Code.filter(alpha2code => {
return !checkAlpha2Code.includes(alpha2code);
});
console.log(countryAlpha2Code)
// Output: [ 'US', 'CA', 'AF', 'AR', 'BR' ]
// Resetting the values again
countryAlpha2Code = ['US', 'CA', 'BD', 'NZ', 'AF' , 'AR' , 'BR']
/**
* Returns the modified array countryAlpha2Code
* which only matches elements with the checkAlpha2Code
*/
countryAlpha2Code = countryAlpha2Code.filter(alpha2code => {
return checkAlpha2Code.includes(alpha2code);
});
console.log(countryAlpha2Code)
// Output: [ 'BD', 'NZ' ]
Solution 17 - Arrays
I see many complaints that remove
method is not in-built. Consider using Set
instead of array - it has add
and delete
methods in-built.
Solution 18 - Arrays
Similar to Abdus Salam Azad answer , but passing array as parameter from //https://love2dev.com/blog/javascript-remove-from-array/
function arrayRemove(arr:[], value:any) {
return arr.filter(function(ele){
return ele != value;
});
}