Learn-JavaScript/6. Function.html at main · Sandeep6135/Learn-JavaScript · GitHub

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<!DOCTYPE html>
<html>

<head>
    <title>JS Function Basics</title>
    <style>
        body {
            font-family: monospace;
            padding: 20px;
        }

        .box {
            border: 1px solid #000;
            padding: 15px;
            margin-bottom: 10px;
        }

        input {
            width: 50px;
        }
    </style>
</head>

<body>

    <h3>1. Input Values</h3>
    <div class="box">
        <input id="num1" type="number" value="10"> +
        <input id="num2" type="number" value="5">
        <button onclick="runLogic()">Run Function</button>
    </div>

    <h3>2. Output</h3>
    <div class="box" id="resultDisplay">
        Click the button to see the math.
    </div>

    <script>
        // --- THE ENGINE (The Function) ---
        // This takes two "parameters" (a and b), processes them, and returns the result.
        function addNumbers(a, b) {
            return a + b;
        }

        // --- THE CONTROLLER ---
        // This grabs the data from the screen and passes it to the engine.
        function runLogic() {
            // 1. Get values from inputs
            let x = Number(document.getElementById("num1").value);
            let y = Number(document.getElementById("num2").value);

            // 2. Call the function and store the "return" value
            let sum = addNumbers(x, y);

            // 3. Display the result
            document.getElementById("resultDisplay").innerHTML =
                "The function returned: <b>" + sum + "</b>";
        }
    </script>

</body>

</html>