3y3

Hide text in plain sight, using invisible characters.

Credit

Credit goes to @yourcompanionAI, source: https://synthetic.garden/3y3.htm

I only re-implemented their algorithm into easy-to-use encode/decode functions.
Below is the original source code:

function secondsightify(t) {
    if ([...t].some(x => (0xe0000 < x.codePointAt(0) && x.codePointAt(0) < 0xe007f))) {
        // 3y3 text detected. Revealing...
        return (t => ([...t].map(x => (0xe0000 < x.codePointAt(0) && x.codePointAt(0) < 0xe007f) ? String.fromCodePoint(x.codePointAt(0) - 0xe0000) : x).join("")))(t)
    } else {
        // No 3y3 text was found, Encoding...
        return (t => [...t].map(x => (0x00 < x.codePointAt(0) && x.codePointAt(0) < 0x7f) ? String.fromCodePoint(x.codePointAt(0)+0xe0000) : x).join(""))(t)
    }
}