Create a single value array in JavaScript

Question

why is the following code showing undefined? Are we not allowed to create an array with a single value? Putting two values won\'t show this error. Is this a pro

Answer 1

You can create an Array with a value using Array.of

let arr = Array.of(8)
console.log(arr)

Answer 2

by new Array(21) you're actually creating an array with 21 elements in it.

If you want to create an array with single value '21', then it's:

var tech = [21];
alert(tech[0]);

Answer 3

new Array(21) creates an array with a length of 21. If you want to create a single-value array, consisting of a number, use square brackets, [21]:

var tech = [ 21 ];
alert(tech[0]);

If you want to dynamically fill an array, use the .push method:

var filler = [];
for(var i=0; i<5; i++){
    filler.push(i); //Example, pushing 5 integers in an array
}
//Filler is now equivalent to: [0, 1, 2, 3, 4]

When the Array constructor receives one parameter p, which is a positive number, an array will be created, consisting of p elements. This feature is can be used to repeat strings, for example:

var repeat = new Array(10);
repeat = repeat.join("To repeat"); //Repeat the string 9x

Answer 4

guys the answer was as simple as this:

<script>
var tech = new Array();
tech.push(21);
alert(tech[0]);
</script>

Answer 5

can use push or use brackets notation , passing single value is like initialize length

var tech = new Array();
tech.push(10);
console.log(tech[0]); 

---

var tech = new Array(5);
console.log(tech.length);  // length = 5
tech.push(10);  // will add as a 6th element i.e. a[5]
console.log(tech.length);   // length = 6
console.log(tech[0]);   // undefined 
console.log(tech[5]);  // 10 

---

or the easy way

var tech = [10];
console.log(tech[0]); 

Answer 6

Here is my solution.

    var tech = new Array(); //create an empty array
    tech.push(21); //Append items to the array
    console.log(tech); // console array the array

Be careful to avoid this; var array = new Array(n), this creates an empty array of length n, then if you push; you will simply append the new item to the end of the array and the new array length will be n+1 and your new array will look like this array = [Empty*21,new item ]