This question already has answers here:
How to push to an array in a particular position?
(4 answers)
How to insert an item into an array at a specific index (JavaScript)
(28 answers)
Closed 7 years ago.
How do I push some data into a certain place in an array?
I am trying the code below:
Keys[1].push({ Keys: "Test" });
But it doesn't seem to work as expected
The method you are looking for is splice
arrayObject.splice(index,0,{Keys:"Test"});
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/splice
Related
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Firestore Update single item in an array field
(2 answers)
how can i update a specific object property within an array in firebase [duplicate]
(2 answers)
Closed 4 months ago.
I want to delete the 0 element of questions array. I've tried this
const documentRef = db.collection(collection).doc(challengeId)
await documentRef.update({
[`stages.0.surveys.0.questions.0`]: firebase.firestore.FieldValue.delete()
})
But it doesn't work. I would appreciate any help. thank you
This question already has answers here:
remove objects from array by object property
(15 answers)
Filter array of objects based on another array in javascript
(10 answers)
How to remove objects from an array which match another array of ids
(4 answers)
Closed 10 months ago.
I need a function that filter some items from array ,like below:
how to make it? Thank you so much in advance !
const users = [
{id:"1",name:"Jane"},
{id:"2",name:"Lucy"},
{id:"3",name:"Li Li"},
{id:"4",name:"Hilton"},
{id:"5",name:"Rose"},
{id:"6",name:"Ha Ha"},
]
//user with this id need to been remove.
const filteredUsers = [
'1','2','5'
]
function filterUsers(allUsers,filteredUsers){
//return after filtered list
}
This question already has answers here:
get the second to last item of an array?
(11 answers)
Closed 10 months ago.
I wanna to get one before last element of array in JavaScript. but in console, when I use this code "array.length -2"dose not work, and it just return me the length of array minus 2.
and when I use this code "array.at[-2]" it returns "undefined"!
const arr = [1,2,3,4,5,6]
console.log(arr[arr.length -2])
//5
This question already has answers here:
Is it possible to create a fixed length array in javascript?
(14 answers)
Closed 3 years ago.
For example, I have an array = []. I want to restrict the array length. How should I initialize it? Is there anything for restricting the size?in Javascript i cant make it? i have a JSON data with 250 length,i want them to restrict to first 20 values?
Define array size. Example:
var arr = new Array(5);
This question already has answers here:
Get the last item in an array
(59 answers)
Closed 8 years ago.
object = [
{"id":1,"name":"Joe"}
{"id":2,"name":"Joe1"}
{"id":3,"name":"Joe2"}
{"id":4,"name":"Joe3"}
]
I want to select {"id":4,"name":"Joe3} but I can't do like object[3] so it there any way to retrieve the last object of an array??
You can get the total length of an array by using length.
array[array.length-1]