pre_eval.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Prefix Evaluation</title>
    <link rel="stylesheet" href="style.css"> 
    <script src="prefix_calculator.js"></script> 
</head>
<body>
    <div class="box">
        <h1>Prefix Evaluation</h1>
        <div class="inst">Enter your prefix expression in the box below</div>

        <div class="input">
            <input type="text" placeholder="Enter your expression" id="expression">
            <button onclick="evaluateExpression()">Evaluate</button>
        </div>

        <div class="result">
            <label for="result">RESULT:</label>
            <input type="text" id="result" readonly>
        </div>

        <div class="btns">
            <button onclick="window.location.href='post_eval.html'">Postfix</button>
            <button onclick="alert('Prefix evaluation is currently active')">Prefix</button>
        </div>

        <div class="madeby">
            <span>By <a href="https://github.com/souhardyaghosh" target="_blank" rel="noopener noreferrer">Souhardya</a> and <a href="https://github.com/msasama" target="_blank" rel="noopener noreferrer">Shazeb</a></span>
        </div>
    </div>

    <script>
        // Wait for the WebAssembly module to be fully initialized
        Module.onRuntimeInitialized = function() {
            var calculatePrefix = Module.cwrap('prefix_calculator', 'number', ['string']);
            
            window.evaluateExpression = function() {
                var expression = document.getElementById('expression').value;
                
                if (!expression) {
                    alert("Please enter a valid expression.");
                    return;
                }
                
                var result = calculatePrefix(expression);
                document.getElementById('result').value = result;
            };
        };
    </script>
</body>
</html>