Basic Functions in JavaScript

1// Method 1: Function Declaration
2function greet(name) {
3    return "Hello, " + name + "!";
4}
5
6console.log("Function declaration:", greet("John"));
7
8// Method 2: Function Expression
9const greet2 = function(name) {
10    return "Hello, " + name + "!";
11};
12
13console.log("Function expression:", greet2("Jane"));
14
15// Method 3: Arrow Function (ES6)
16const greet3 = (name) => {
17    return "Hello, " + name + "!";
18};
19
20console.log("Arrow function:", greet3("Bob"));
21
22// Method 4: Arrow Function (one-liner)
23const greet4 = name => "Hello, " + name + "!";
24
25console.log("Arrow one-liner:", greet4("Alice"));
26
27// Method 5: Function with default parameters
28function greet5(name = "Guest") {
29    return "Hello, " + name + "!";
30}
31
32console.log("\nWith default:");
33console.log(greet5("Tom"));
34console.log(greet5());
35
36// Method 6: Function with multiple parameters
37function calculate(a, b, operation = 'add') {
38    switch(operation) {
39        case 'add':
40            return a + b;
41        case 'subtract':
42            return a - b;
43        case 'multiply':
44            return a * b;
45        case 'divide':
46            return a / b;
47        default:
48            return "Invalid operation";
49    }
50}
51
52console.log("\nCalculate function:");
53console.log("10 + 5 =", calculate(10, 5, 'add'));
54console.log("10 - 5 =", calculate(10, 5, 'subtract'));
55console.log("10 * 5 =", calculate(10, 5, 'multiply'));
56console.log("10 / 5 =", calculate(10, 5, 'divide'));