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]

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>