JSFiddle - React, Tailwind, and code Playground

HTML

<textarea id="ta" rows="10" cols="50"></textarea>

JavaScript

$(function () {
    var ta = $('#ta');
    ta.keyup(function () {
        var flag = !0;
        var arr = this.value.split(/\n/);
        if (3 < arr.length) {
            flag = !1;
        } else {
            $.map(arr, function (val, idx) {
                if (20 < val.length) {
                    flag = !1;
                    return false;
                }
            });
        }
        if (!flag) { // invalid
            ta.css('backgroundColor', '#fcc');
        } else {
            ta.css('backgroundColor', '#fff');
        }
    });
});