Scientific calcuoator v3

<html>
<head>
<title>This is for my friends!</title>

<style>
body {margin: 0; background-color: #EFDB2F; text-align: center}
p {font-size: 0px}
td {width: 19vw; height: 13.8vh; text-align: center; font-size: 25px; font-weight: bold; color: black; border: 1px solid white}
td:hover {background-color: #CDBA1E}
input {width: 100%; height: 100%; border: none; font-size: 25px; font-weight: bold; padding: 0px 5px}
#shiftBtn {background-color: yellow}
</style>
</head>
<body>
<p id=myPara></p>
<p id=myAns>0</p>
<table>
    <tr>
    <td colspan=5><input id=result readonly></td>
    </tr>

    <tr>
    <td onclick="shiftFn(1)" id=shiftBtn>Shift</td>
    <td onclick="trigo('sin')">sin</td>
    <td onclick="trigo('cos')">cos</td>
    <td onclick="trigo('tan')">tan</td>
    <td onclick="input('!')">!</td>
    </tr>

    <tr>
    <td onclick="input('^(')">^</td>
    <td onclick="sqrt()">sqrt</td>
    <td onclick="leftParen()">(</td>
    <td onclick="input(')')">)</td>
    <td onclick="log(1)">log</td>
    </tr>

    <tr>
    <td onclick="input('7')">7</td>
    <td onclick="input('8')">8</td>
    <td onclick="input('9')">9</td>
    <td onclick="del()">DEL</td>
    <td onclick="ac()">AC</td>
    </tr>

    <tr>
    <td onclick="input('4')">4</td>
    <td onclick="input('5')">5</td>
    <td onclick="input('6')">6</td>
    <td onclick="multOrDiv('mult')">×</td>
    <td onclick="multOrDiv('div')">÷</td>
    </tr>

    <tr>
    <td onclick="input('1')">1</td>
    <td onclick="input('2')">2</td>
    <td onclick="input('3')">3</td>
    <td onclick="input('+')">+</td>
    <td onclick="input('-')">-</td>
    </tr>

    <tr>
    <td onclick="input('0')">0</td>
    <td onclick="input('.')">.</td>
    <td onclick="piOrE('pi')">π</td>
    <td onclick="ans()">Ans</td>
    <td onclick="equal()">=</td>
    </tr>
</table>
<script>
    function shiftFn(ken) {
    var shift = document.getElementById("shiftBtn") ;
    var arr = document.getElementsByTagName("td") ;
    if (ken == 1) {
        shift.setAttribute("onclick", "shiftFn(0)") ;
        shift.style.backgroundColor = "orange" ;
        arr[2].innerHTML = "sin<sup>-1</sup>" ;
        arr[2].setAttribute("onclick", "trigo1('sin')") ;
        arr[3].innerHTML = "cos<sup>-1</sup>" ;
        arr[3].setAttribute("onclick", "trigo1('cos')") ;
        arr[4].innerHTML = "tan<sup>-1</sup>" ;
        arr[4].setAttribute("onclick", "trigo1('tan')") ;
        arr[10].innerHTML = "ln" ;
        arr[10].setAttribute("onclick", "log(0)") ;
        arr[28].innerHTML = "\u0065" ;
        arr[28].setAttribute("onclick", "piOrE('e')") ;
    } else {
        shift.setAttribute("onclick", "shiftFn(1)") ;
        shift.style.backgroundColor = "yellow" ;
        arr[2].innerHTML = "sin" ;
        arr[2].setAttribute("onclick", "trigo('sin')") ;
        arr[3].innerHTML = "cos" ;
        arr[3].setAttribute("onclick", "trigo('cos')") ;
        arr[4].innerHTML = "tan" ;
        arr[4].setAttribute("onclick", "trigo('tan')") ;
        arr[10].innerHTML = "log" ;
        arr[10].setAttribute("onclick", "log(1)") ;
        arr[28].innerHTML = "\u03C0" ;
        arr[28].setAttribute("onclick", "piOrE('pi')") ;
    }
}

function input(sun) {
    var x = document.getElementById("result") ;
    var y = document.getElementById("myPara") ;
    x.value += sun ;
    y.innerHTML += sun ;
}

function factorial(shirious) {
    if (Number.isInteger(shirious)) {
        if (shirious < 2) return 1 ;
        return shirious * factorial(shirious - 1) ;
    }
}

function sqrt() {
    var x = document.getElementById("result") ;
    var y = document.getElementById("myPara") ;
    x.value += "sqrt(" ;
    y.innerHTML += (/[\d)IE]/.test(y.innerHTML.slice(-1))) ?
    " * Math.sqrt(" : "Math.sqrt(" ;
}

function leftParen() {
    var x = document.getElementById("result") ;
    var y = document.getElementById("myPara") ;
    x.value += "(" ;
    y.innerHTML += (/[\d)IE]/.test(y.innerHTML.slice(-1))) ?
    " * (" : "(" ;
}

function trigo(hatsyrei) {
    var x = document.getElementById("result") ;
    var y = document.getElementById("myPara") ;
    x.value += hatsyrei + "(" ;
    y.innerHTML += (/[\d)IE]/.test(y.innerHTML.slice(-1))) ?
    " * Math." + hatsyrei + "(Math.PI / 180 * " : "Math." + hatsyrei + "(Math.PI / 180 * " ;
}

function trigo1(valentin) {
    var x = document.getElementById("result") ;
    var y = document.getElementById("myPara") ;
    x.value += valentin + "\u207B\u00B9("
    y.innerHTML += (/[\d)IE]/.test(y.innerHTML.slice(-1))) ?
    " * 180 / Math.PI * Math.a" + valentin + "(" : "180 / Math.PI * Math.a" + valentin + "(" ;
}

function ac() {
    var x = document.getElementById("result") ;
    var y = document.getElementById("myPara") ;
    x.value = y.innerHTML = "" ;
}

function ans() {
    var x = document.getElementById("result") ;
    var y = document.getElementById("myPara") ;
    var z = document.getElementById("myAns") ;
    x.value += "Ans" ;
    y.innerHTML += (/[\d)IE]/.test(y.innerHTML.slice(-1))) ?
    " * " + z.innerHTML : z.innerHTML ;
}

Scientific calcuoator v3

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