JS DOM: escape, unescape ❌

The Escape Method

escape is a string property of the the Global Object.

escape is deprecated.

escape(str)

Return a new string from str with some characters percent encoded.

console.log(escape("A"));
// A

console.log(escape("~"));
// %7E

console.log(escape(" "));
// %20

console.log(escape("α"));
// %u03B1

/*
α
GREEK SMALL LETTER ALPHA
ID 945
HEXD 3B1
UTF8  CE B1
UTF16 3B1
*/

console.log(escape("🦋"));
// %uD83E%uDD8B

/*
🦋
Name: BUTTERFLY
ID 129419
HEXD 1F98B
UTF8  F0 9F A6 8B
UTF16 D83E DD8B
*/

Forms of the Changed Char

Changed characters are in this form:

• %DD → for char with codepoint ≺ 256.
• %uDDDD → for char with codepoint ≥ 256.

, where DD is 2 digits of hexadecimal and DDDD is 4 digits of hexadecimal.

they are the byte sequence of the character in UTF-16 encoding. .

〔see JS: String Index Code Unit〕

Chars Not Changed

// all chars that escape() does not change
console.log((Array.from((Array(128)).keys(), (x) => String.fromCharCode(x)).filter((x) => (escape(x) === x))).join(""));
// *+-./0123456789@ABCDEFGHIJKLMNOPQRSTUVWXYZ_abcdefghijklmnopqrstuvwxyz

All other chars are replaced.

unescape

Use unescape function to decode a string encoded with escape.