Convert character to ASCII code in JavaScript

From characters to code with charCodeAt

Every character in JavaScript is encoded using UTF-16. In this context, charCodeAt() retrieves a UTF-16 code unit at the specified index. This is not the traditional ASCII code, but it works the same for ASCII characters (those between 0-127). Remember, charCodeAt beam isn't strong enough for extended character sets.

Dealing with non-BMP Unicode characters

For characters outside the realm of the Basic Multilingual Plane (BMP), the eco-friendly JavaScript uses two 16-bit code units. In these cases, charCodeAt falls short, like when trying to fill an Olympic pool with a garden hose. Use codePointAt() to grab the full Unicode code point, even for these big fish:

let smiley = '😊'; // Prepare the emoji
console.log(smiley.codePointAt(0)); // Gotcha! Displays 128522
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Making ASCII codes talk with fromCharCode

To translate ASCII codes back to characters, use String.fromCharCode(). This function can also string along multiple ASCII codes into a coherent sentence:

console.log(String.fromCharCode(65)); // Back to 'A'
console.log(String.fromCharCode(72, 101, 108, 108, 111)); // 'Hello' from the other side!
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Non-BMP Unicode characters unravelled

Let's tempt fate and dive into the realm of non-BMP characters:

let nonBmpChar = '𐍈'; // A character from the Gothic letters
let codeUnit = nonBmpChar.charCodeAt(0); // Trying the old trick... and fails!
let codePoint = nonBmpChar.codePointAt(0); // I've got the power! Shows correct code point
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Non-BMP Unicode characters are like tricky kids at hand - they include emojis, symbols sets, and anything more than what meets the eye.

ASCII code lookup

An ASCII reference is your map in the character encoding universe. Like finding your way to the newline character ('\n') that sits on ASCII code 10:

console.log('\n'.charCodeAt(0)); // 10, just like promised!
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Look for traps, find alternatives

Caution, adventurers! charCodeAt() might take a break when faced with non-ASCII characters. Use the Buffer classes in Node.js, your trusted companion for binary data journeys, or the TextEncoder and TextDecoder APIs in your browser for the ultimate encoding/decoding challenge.