JSFiddle - React, Tailwind, and code Playground

by riateche

HTML

<input id="i1">

JavaScript

var a = [];
$("#i1").keydown(function(e) {
    var letter = String.fromCharCode(e.keyCode);
    if (a.indexOf(letter) < 0) {
        a.push(letter);
        console.log(a);
    }
}).keyup(function(e) {
    var letter = String.fromCharCode(e.keyCode);
    if ( (n = a.indexOf(letter)) >= 0) {
        a.splice(n);
    }
    console.log(a);
})