JavaScript: Unicode Escape Sequence

Character in string can be represented by a escape sequence. For example, "\u0041" is the same as "A".

There are 2 syntax:

\u4_hexd_digits

represent a character whose Codepoint can be represented by 4 Hexadecimal digits or less. Must pad 0 in front if not 4 digits

// represent a char by its codepoint in hexadecimal
// must pad 0 in front if not 4 digits
console.log("\u0041" === "A");
console.log("\u03b1" === "α");

\u{hexadecimal}

represent any character whose Codepoint is the Hexadecimal

(new in ES2015)

// represent any character by their Codepoint
console.log("\u{41}" === "A");

// if 0 padded, still works
console.log("\u{000000000041}" === "A");

// any unicode char works
console.log("\u{3b1}" === "α");
console.log("\u{1f602}" === "😂");

// unicode escape can be used in identifiers

// deno-fmt-ignore
const \u{3b1} = 123;
console.log(α === 123);

Unicode escape sequence can be used in:

• string literals
• regular expression literals
• string template literals
• identifiers
• any function that takes argument of Unicode codepoint can also be replaced by Unicode escape sequence.

Within a comment, Unicode escape sequence is ignored.