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HTML 

              
                <html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Annotatable Calculator</title>
</head>
<body>
  <h1>Annotatable Calculator</h1>
  <div class="wrapper">
    <div class="dash">
      <form id = "io">
        <input type="text" id = "annotation" placeholder="Optional annotation">
        <input type="text" id = "formula" placeholder="Press Enter to Calculate">
      </form>
      <button class="clear" id="clearAnnotation">Clear annotation</button>
      <button class="clear" id="clearFormula">Clear formula</button>
      <button class="clear" id="clearHistory">Clear history</button>
    </div>
    <div class="keyboard">
      <div class="row">
        <button class="num">7</button>
        <button class="num">8</button>
        <button class="num">9</button>
        <button class="oper">/</button>
      </div>
      <div class= "row">
        <button class="num">4</button>
        <button class="num">5</button>
        <button class="num">6</button>
        <button class="oper">*</button>
      </div>
      <div class="row">
        <button class="num">1</button>
        <button class="num">2</button>
        <button class="num">3</button>
        <button class="oper">-</button>
      </div>
      <div class="row">
        <button id="ce">CE</button>
        <button class="num">0</button>
        <button class="oper">**</button>
        <button class="oper">+</button>
      </div>
      <div class="row">
        <button id="ac">AC</button>
        <button class="num">.</button>
        <button id="sign">±</button>
        <button class="equal">=</button>
      </div>
    </div>
    <div id="history">
      <div id="historyTitle"><h3>History</h3></div>
      <div id="historyContent"></div>
    </div>
  </div>
  <br>
  <br> 
  <footer>Product by Zack Light</footer>
</body>
</html>
!

CSS 

              
                body {
 font-family: Arial, sans-serif;
 text-align: center;
}

a {
  text-decoration: none;
}

button:active {
  transform: translate(0px, 3px);
  box-shadow: none;
}

.clear, input{
  display: block;
  margin-left: 2px;
  margin-bottom: 5px;
  font-size: 1em;
}

.clear {
   width: 200px;
}

.keyboard button {
    display: inline-block;
    text-decoration: none;
    font-weight: bold;
    color: #fff;
    background-color: black;
    font-size: 1.5em;
}

#ac, #ce, .keyboard .equal {
  background-color: maroon;
  color: white;
}

.keyboard .oper, .keyboard #sign {
    background-color: Indigo;
}

calculator {
  border: 1px solid black;
}

#historyContent {
  border: 1px solid black;
  margin: 20px 0;
}

.historical {
  vertical-align: middle;
  border: 1px solid black;
}

#io {
  margin: 15px 0;
  display: grid;
  grid-gap: .4em;
}

row {
  display: block;
}

.keyboard {
  display: grid;
  grid-gap: 10px;
  grid-template-rows: repeat(5, 50px);
  justify-items: center;
}

.row {
    display: grid;
    grid-gap: 5px;
    grid-template-columns: repeat(4, 50px);
}

.wrapper {
  display: grid;
    grid-gap: 5px;
    grid-template-columns: 1fr 1fr 1fr;
}
!

JS 

              
                /*
1. make mouse move
2. clear anno after calc
3. make anno italic
4. delete individual calcs
5. reduce repeatition & inconsistency 

1. leads to calcs?
2. clear history. No more calcs.
*/

let calc = "";
let counter = 1;
const opers = "+-**/";

function finalUpdate() {
  $("#formula").val(calc)
}

function evaluate() {
  if ($("#annotation").val() != "" | $("#formula").val() != "") {
    let anno = $("#annotation").val()
    let toBeInserted = ""
    if (anno != "") {
      toBeInserted = "<div class = 'historical' id =" + counter + " >" + counter + ". " + anno + ":" + "<br>" + calc + "=<br>" + eval(calc) + "</div>"
    }
    else {
      toBeInserted = "<div class = 'historical' id =" + counter + " >" + counter + ". "  + calc + "=<br>" + eval(calc) + "</div>"
    }
    $("#historyContent").prepend(toBeInserted)
    counter++
    calc = ""
    finalUpdate()
  }
}

function numUpdate(para) {
  calc += para
   finalUpdate()
}

function operUpdate(para) {
  if (calc.length !== 0) {
      const last = calc.slice(-1)
      if (opers.indexOf(last) === -1 ){
        calc += para
      }
    else if (opers.indexOf(last) >= 0 && calc.slice(-2) !== "**") {
         calc = calc.slice(0, -1) + para
      }
    else {
      calc = calc.slice(0, -2) + para
    }
      finalUpdate()
    }
}

function ceUpdate() {
  while (true) {
    if (opers.indexOf(calc.slice(-1)) >= 0) {
        break
        }
    calc = calc.slice(0, -1)
  }
  finalUpdate()
}

function acUpdate() {
    calc = ""
    finalUpdate()
}

function signUpdate() {
  calc = "-1*(" + calc + ")"
  finalUpdate()
}

$(document).ready(function () {
  $("#clearAnnotation").click(function () {
    $("#annotation").val("")
  })
  
  $("#clearFormula").click(function () {
    acUpdate()
  })
  
  $("#clearHistory").click(function () {
    document.getElementById("history").innerHTML = "History"
    let counter = 1
  })
  
  $(".num").click(function () {
    let para = this.innerHTML
   numUpdate(para)
  })
  
  $(".oper").click(function() {
    let para = this.innerHTML
    operUpdate(para)
  })
  
    $("#ac").click(acUpdate()
  )
  
  $("#ce").click(function() {
    ceUpdate()
  })
  
  $(".equal").click(function() {
    evaluate()
    $("#annotation").val("")
  })
  
  $("#sign").click(function() {
    signUpdate()
  })
  
  $( "#formula" ).change(function() {
    calc = $("#formula").val()
    evaluate()
  })
}
)
!
999px

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