Web-Calculator-Tutorial/index.html at main · APHS-Hack-Club/Web-Calculator-Tutorial · GitHub

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Calculator</title>
    <link rel="stylesheet" href="styles.css">
</head>
<body>

    <div class="calculator">
        <input id="display" type="text" readonly placeholder="0">
        <div class="buttons-container">
            <button onclick="clearDisplay()">C</button>
            <button onclick="addDigit('(')">(</button>
            <button onclick="addDigit(')')">)</button>
            <button class="operation" onclick="changeOperator('/')">/</button>

            <button onclick="addDigit('1')">1</button>
            <button onclick="addDigit('2')">2</button>
            <button onclick="addDigit('3')">3</button>
            <button class="operation" onclick="changeOperator('+')">+</button>

            <button onclick="addDigit('4')">4</button>
            <button onclick="addDigit('5')">5</button>
            <button onclick="addDigit('6')">6</button>
            <button class="operation" onclick="changeOperator('-')">-</button>

            <button onclick="addDigit('0')">0</button>
            <button onclick="addDigit('.')">.</button>
            <button class="equals" onclick="calculateResult()">=</button>
        </div>
    </div>

    <script>
        let operator = '';
        let num1 = '0';
        let num2 = '';
        // Let's us know if we are inputting the num2 (after operator) or num1 (before operator)
        let afterOperator = false;

        function addDigit(val) {
            if (afterOperator){
                num2 += val;
                document.getElementById('display').value = num2;
            } else {
                num1 = (num1 == '0') ? val : num1 + val;
                document.getElementById('display').value = num1;
            }
        }

        function changeOperator(val) {
            operator = val;
            calculateResult()
            afterOperator = true;
        }

        function clearDisplay() {
            operator = ''
            num1 = '0'
            num2 = ''
            afterOperator = false;
            document.getElementById('display').value = '';
        }

        function calculateResult() {
            if (num1=='' || num2=='') return;

            num1 = 0; // EDIT THIS
            num2 = '';
            document.getElementById('display').value = num1;
            afterOperator = false;
        }

    </script>

</body>
</html>