javascript create empty array of a given size – Even if we have a good project plan and a logical concept, we will spend the majority of our time correcting errors abaout javascript and javascript. Furthermore, our application can run without obvious errors with JavaScript, we must use various ways to ensure that everything is operating properly. In general, there are two types of errors that you’ll encounter while doing something wrong in code: Syntax Errors and Logic Errors. To make bug fixing easier, every JavaScript error is captured with a full stack trace and the specific line of source code marked. To assist you in resolving the JavaScript error, look at the discuss below to fix problem about javascript create empty array of a given size.
Problem :
in javascript how would I create an empty array of a given size
Psuedo code:
X = 3;
createarray(myarray, X, "");
output:
myarray = ["","",""]
Solution :
1) To create new array which, you cannot iterate over, you can use array constructor:
Array(100) or new Array(100)
2) You can create new array, which can be iterated over like below:
a) All JavaScript versions
- Array.apply:
Array.apply(null, Array(100))
b) From ES6 JavaScript version
- Destructuring operator:
[...Array(100)] - Array.prototype.fill
Array(100).fill(undefined) - Array.from
Array.from({ length: 100 })
You can map over these arrays like below.
-
Array(4).fill(null).map((u, i) => i)[0, 1, 2, 3] -
[...Array(4)].map((u, i) => i)[0, 1, 2, 3] -
Array.apply(null, Array(4)).map((u, i) => i)[0, 1, 2, 3] -
Array.from({ length: 4 }).map((u, i) => i)[0, 1, 2, 3]
var arr = new Array(5);
console.log(arr.length) // 5
We use Array.from({length: 500}) since 2017.
As of ES5 (when this answer was given):
If you want an empty array of undefined elements, you could simply do
var whatever = new Array(5);
this would give you
[undefined, undefined, undefined, undefined, undefined]
In newer versions, this now gives
[empty × 5]
See this other question on the difference between empty and undefined.
If you wanted it to be filled with empty strings, you could do
whatever.fill('');
which would give you
["", "", "", "", ""]
And if you want to do it in one line:
var whatever = Array(5).fill('');
Try using while loop, Array.prototype.push()
var myArray = [], X = 3;
while (myArray.length < X) {
myArray.push("")
}
Alternatively, using Array.prototype.fill()
var myArray = Array(3).fill("");
In 2018 and thenceforth we shall use [...Array(500)] to that end.
If you want to create anonymous array with some values so you can use this syntax.
var arr = new Array(50).fill().map((d,i)=>++i)
console.log(arr)You can use both javascript methods repeat() and split() together.
" ".repeat(10).split(" ")
This code will create an array that has 10 item and each item is empty string.
const items = " ".repeat(10).split(" ")
document.getElementById("context").innerHTML = items.map((item, index) => index)
console.log("items: ", items)<pre id="context">
</pre>