现场演示：我的 HTML 文档

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <title>JavaScript ES6 Arrow Functions Variations</title>
</head>
<body>
    <script>
    // Single parameter, single statement
    var greet = name => document.write("Hi " + name + "!");
    greet("Peter"); // Hi Peter!
    document.write("<br>");
        
    // Multiple arguments, single statement
    var multiply = (x, y) => x * y;
    document.write(multiply(2, 3)); // 6
    document.write("<br>");
    
    // Single parameter, multiple statements
    var test = age => {
        if(age > 18) {
            document.write("Adult");
        } else {
            document.write("Teenager");
        }
    }
    test(21); // Adult
    document.write("<br>");
    
    // Multiple parameters, multiple statements
    var divide = (x, y) => {
        if(y != 0) {
            return x / y;
        }
    }
    document.write(divide(10, 2)); // 5
    document.write("<br>");
    
    // No parameter, single statement
    var hello = () => document.write('Hello World!');
    hello(); // Hello World!
    </script>
</body>
</html>

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<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <title>JavaScript ES6 Arrow Functions Variations</title>
</head>
<body>
    <script>
    // Single parameter, single statement
    var greet = name => document.write("Hi " + name + "!");
    greet("Peter"); // Hi Peter!
    document.write("<br>");
        
    // Multiple arguments, single statement
    var multiply = (x, y) => x * y;
    document.write(multiply(2, 3)); // 6
    document.write("<br>");
    
    // Single parameter, multiple statements
    var test = age => {
        if(age > 18) {
            document.write("Adult");
        } else {
            document.write("Teenager");
        }
    }
    test(21); // Adult
    document.write("<br>");
    
    // Multiple parameters, multiple statements
    var divide = (x, y) => {
        if(y != 0) {
            return x / y;
        }
    }
    document.write(divide(10, 2)); // 5
    document.write("<br>");
    
    // No parameter, single statement
    var hello = () => document.write('Hello World!');
    hello(); // Hello World!
    </script>