How Can I Create a Range of Numbers or Characters in JavaScript?

Does JavaScript Have a Range Function?

JavaScript does not natively include a "range()" method, like PHP's, to generate a range within specified bounds. However, there are several ways to achieve this using built-in methods or third-party libraries.

Numbers

To generate a range of numbers, you can use the following syntax:

[...Array(5).keys()]; // [0, 1, 2, 3, 4]

Character Iteration

For character iteration, you can employ this code:

String.fromCharCode(...[...Array('D'.charCodeAt(0) - 'A'.charCodeAt(0) + 1).keys()].map(i => i + 'A'.charCodeAt(0))); // "ABCD"

Iteration

To iterate over both numbers and characters simultaneously, try:

for (const x of Array(5).keys()) {
  console.log(x, String.fromCharCode('A'.charCodeAt(0) + x));
} // 0,"A" 1,"B" 2,"C" 3,"D" 4,"E"

Functions

To create reusable functions, you can:

function range(size, startAt = 0) {
  return [...Array(size).keys()].map(i => i + startAt);
}

function characterRange(startChar, endChar) {
  return String.fromCharCode(...range(endChar.charCodeAt(0) -
            startChar.charCodeAt(0), startChar.charCodeAt(0)))
}

console.log(range(5)); // [0, 1, 2, 3, 4]
console.log(characterRange('A', 'C')); // "ABC"

Lodash.js Library

Lodash.js includes a _.range() function:

_.range(10); // [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
_.range(1, 11); // [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

These techniques provide viable alternatives to PHP's range() function within JavaScript.

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