Implement unary operator buttons + tidying up

Currently only square root available with current button layout but
should now be extensible to other unary functions. There is a bug where
applying a unary function allows editing the number, but changing this
by setting newNum to true prevents performing other operations with the
results of unary operations.

index.html

@@ -14,7 +14,7 @@
         <div class="button-row">
           <button id="C" class="clear">C</button>
           <button id="CE" class="clear">CE</button>
-          <button id="root" class="unaryOperators">√</button>
+          <button id="sqrt" class="unaryOperators">√</button>
           <button id="div" class="binaryOperators">/</button>
         </div>
         <div class="button-row">

script.js

@@ -22,7 +22,6 @@ const Calculator = {
     };
   },
   applyUnaryOperation: function (operator, x) {
-    Screen.newNum = true;
     Screen.display(UnaryOperators[operator](x));
   },
 
@@ -35,6 +34,11 @@ const Calculator = {
     }
     Calculator.currOperation = null;
   },
+
+  clear: function () {
+    Calculator.currOperation = null;
+    Calculator.prevOperation = null;
+  },
 };
 
 // Store operations to be used by the calculator
@@ -141,10 +145,22 @@ function binaryOperatorButtonPress(event) {
     // operations if another operator button is pressed
     Calculator.execute(num);
   }
-  Calculator.newBinaryOperation(operator, +Screen.screenSelector.textContent);
+  Calculator.newBinaryOperation(operator, num);
   Screen.newNum = true;
 }
 
+const unaryOperatorButtons = document.querySelector(".unaryOperators");
+unaryOperatorButtons.addEventListener("click", unaryOperatorButtonPress);
+function unaryOperatorButtonPress(event) {
+  if (Screen.screenSelector.textContent.includes("ERR"))
+    return; // do nothing if error
+  else if (Screen.newNum) Calculator.clear();
+  let operator = event.target.id;
+  num = +Screen.screenSelector.textContent;
+  Screen.display(UnaryOperators[operator](num));
+  // Screen.newNum = true;
+}
+
 const equalsButton = document.querySelector("#equals");
 equalsButton.addEventListener("click", equalsButtonPress);
 function equalsButtonPress(_) {
@@ -161,14 +177,10 @@ function clearButtonPress(event) {
   Screen.screenSelector.textContent = "0";
   if (event.target.id == "C") {
     // Clear all
-    Calculator.currOperation = null;
-    Calculator.prevOperation = null;
+    Calculator.clear();
   }
 }
 
-const unaryOperatorButtons = document.querySelector("#root");
-unaryOperatorButtons.querySelectorAll(".unaryOperators");
-
 const signButton = document.querySelector("#sign");
 const decimalButton = document.querySelector("#decimal");