🟨JavaScript and ASCII

handling user input based on keystrokes or any single-character input

ASCII (American Standard Code for Information Interchange) refers to a way to encode a character into a number.

For example, the uppercase A corresponds with an ASCII code of 65, while the lowercase a corresponds to 97.

ASCII has 128 characters in all covering the letters A-Z (and a-z), numbers (0-9), some symbols (!, @, #, ...) and some other characters for line breaks and tab indents.

ASCII use case

ASCII's 128 characters makes it a limited set, which makes newer systems like Unicode better for storing all the characters of all the world's langauges. However, we still use ASCII for user input from a keyboard (especially an English language one, which is the most widely used).

When a user presses a button on a keyboard, the keyboard translates the "button press" into an ASCII value (you can try this single-page add call keycode.info to learn more!)

Using ASCII values with JavaScript allows programming keystroke shortcuts for a website.

Finding the ASCII value of a character with charCodeAt()

We can lookup the ASCII value of a character in a JavaScript String with charCodeAt():

let myString = "ASCII always"

console.log(myString.charCodeAt(0))
// 65 for A

console.log(myString.charCodeAt(6))
// 97 for a

Finding a human-readable character based on a given ASCII value with fromCharCode()

The opposite of charCodeAt() is fromCharCode(),which takes an ASCII value and converts it into a String character:

let character = String.fromCharCode(65)

console.log(character)
// A

Once again, the website keycode.info allows you to check your ASCII values!