This question already has answers here:
How do I empty an array in JavaScript?
(17 answers)
Closed 6 years ago.
I have an array eg: a[3,4,5,6,7,8]. I want to remove all the element in one time and make array as an empty array. How to remove all the element of an array.
My code
var a = [2,3,4,5,6];
for(var i=0; I<a.length; i++){
a.remove();
}
a.length = 0;
This is all what you need
var a = [2,3,4,5,6];
console.log(a);
a.length = 0;
console.log(a);
Do a.length = 0; if you don't want to lose references. Do a = []; if you want to lose references.
Related
This question already has answers here:
Create an array with same element repeated multiple times
(25 answers)
Closed 2 years ago.
I currently have this array: var arr = []
How do I push multiple "hello" strings into the array using a for loop?
I tried
var newArray = arr.push("hello")10;
try new Array forEach or simple for-loop should work.
var arr = [];
// method 1
new Array(5).fill(0).forEach(() => arr.push("hello"));
// alternate method
for (let i = 0; i < 5; i++) {
arr.push("world");
}
console.log(arr);
// Updating based on suggesion #mplungjan, quick way without loop.
var arr2 = Array(10).fill("hello");
console.log(arr2)
This question already has answers here:
Array.fill(Array) creates copies by references not by value [duplicate]
(3 answers)
Closed 4 years ago.
When i use Array.fill to fill a multidimensional array, i get a weird behaviour when pushing to one of the arrays:
var arr = Array(2).fill([]);
arr[0].push(5);
console.log(arr);
//=> prints [[5], [5]]
fill is essentially doing this:
var content = [];
for (var i = 0; i < 2; i += 1) {
arr[i] = content;
}
So, your array will have a reference to the array you've passed to fill in each property.
It sounds weird, but what your code actually does is create an array ([]) and put a reference for that array in each of the items of the Array(2). So whenever you change that reference - every array that is referenced to that Array is changed.
It's exactly the same as:
var a = [];
var arr = Array(2).fill(a);
a.push(5);
console.log(arr[0][0], arr[1][0]);
a[0] = 2;
console.log(arr[0][0], arr[1][0]);
You can see that the values inside the arr are affected by the change to the a array.
This question already has answers here:
How to use a variable for a key in a JavaScript object literal?
(16 answers)
Closed 7 years ago.
I need to fill an array object as like below using integer variable.
for(i=1; i<=2; i++)
arr[i].push({i:(100 * i)})
Expected result is:
arr = [{ 1:100,2:200},{1:100,2:200}]
Problem is, array created as like below
arr = [{i:100,i:200},{i:100,i:200}]
You need to push to arr instead of arr[i].
Also, you can't use a variable as a key in json directly.
var arr = [];
for(i=1; i<=2; i++)
{
var b = {};
b[i] = 100*i;
arr.push({[i]:(i*100)});
}
console.log(arr);
This question already has answers here:
Create an array with same element repeated multiple times
(25 answers)
Closed 7 years ago.
I'm wondering if there is a way to create javascript/jquery array in one-liner to receive something like:
my_array = ['-', '-', ,'-' ,'-']
Idea is that array should be created with dynamic length and all values filled with given value.
Thanks in advance!
Try:
var total = 4;
var my_array = new Array(total + 1).join("-").split("");
document.write(JSON.stringify(my_array))
.fill Support The native function will be added in (ECMAScript 6), but for now is not available.
if(!Array.prototype.fill){
Array.prototype.fill = function(val){
for (var i = 0; i < this.length; i++){
this[i] = val
}
return this
}
}
var my_array = new Array(4).fill("-"); //returns ["-","-","-","-"]
Try to use:
Array.apply(null, new Array(63)).map(String.prototype.valueOf,"-")
This question already has answers here:
Loop (for each) over an array in JavaScript
(40 answers)
Closed 8 years ago.
Okay, take it easy on me. I am really new to JavaScript and having issues getting the for-each loop to work correctly. Any Tips?
var array = ["Bob", "Nancy", "Jessie", "Frank"];
var arrayLength = myStringArray.length;
for (var i = 0; i < arrayLength; i++) {
document.write(array);
}
var myArray = ["Bob", "Nancy", "Jessie", "Frank"];
var arrayLength = myStringArray.length;
for (var i = 0; i < arrayLength; i++) {
//Do something with element myArray[i]
}
I guess you need something like this.
Edit: Your array has only 4 elements. In the 2nd line I save the length of your array (4 elements --> length is 4) in the variable 'arrayLength'. Then I wrote a simple for-loop which cycles the 'i' from 0 till 3 so you can access your elements from your array as 'myArray[i]'.
The for in is used to iterate over properties on the object. It is not the same as a regular foreach. Use a for loop for this