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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Dynamic Function Assignment</title>
    <script>
        // Define multiple functions
        function greetMorning() {
            alert("Good Morning!");
        }
​
        function greetEvening() {
            alert("Good Evening!");
        }
​
        // Variable to hold the current function
        var currentGreetFunction;
​
        // Function to change the current greet function
        function setGreetFunction(timeOfDay) {
            if (timeOfDay === "morning") {
                currentGreetFunction = greetMorning;
            } else if (timeOfDay === "evening") {
                currentGreetFunction = greetEvening;
            }
        }
​
        // Function to execute the current greet function
        function executeGreetFunction() {
            if (currentGreetFunction) {
                currentGreetFunction();
            } else {
                alert("No greeting function set.");
            }
        }
    </script>
</head>
<body>
    <button onclick="setGreetFunction('morning')">Set Morning Greeting</button>
    <button onclick="setGreetFunction('evening')">Set Evening Greeting</button>
    <button onclick="executeGreetFunction()">Greet</button>
</body>
</html>