javascript-patterns/design-patterns/visitor.html at master · lovejavaee/javascript-patterns · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
<!doctype html>
<html lang="en">
	<head>
		<title>JavaScript Patterns</title>
		<meta charset="utf-8">
	</head>
	<body>
		<script>
			/* Title: Visitor
			 Description: Represent an operation to be performed on the elements of an object structure.
			 Visitor lets you define a new operation without changing the classes of the elements on which it operates.
			 */

			var Employee = function (name, salary, vacation) {
				var self = this;

				this.accept = function (visitor) {
					visitor.visit(self);
				};

				this.getName = function () {
					return name;
				};

				this.getSalary = function () {
					return salary;
				};

				this.setSalary = function (sal) {
					salary = sal;
				};

				this.getVacation = function () {
					return vacation;
				};

				this.setVacation = function (vac) {
					vacation = vac;
				};
			};

			var ExtraSalary = function () {
				this.visit = function (emp) {
					emp.setSalary(emp.getSalary() * 1.1);
				};
			};

			var ExtraVacation = function () {
				this.visit = function (emp) {
					emp.setVacation(emp.getVacation() + 2);
				};
			};

			// log helper
			var log = (function() {
				var log = "";

				return {
					add: function(msg) { log += msg + "\n"; },
					show: function() { alert(log); log = ""; }
				}
			})();

			//example
			function run() {

				var employees = [
					new Employee("John", 10000, 10),
					new Employee("Mary", 20000, 21),
					new Employee("Boss", 250000, 51)
				];

				var visitorSalary = new ExtraSalary();
				var visitorVacation = new ExtraVacation();

				for (var i = 0, len = employees.length; i < len; i++) {
					var emp = employees[i];

					emp.accept(visitorSalary);
					emp.accept(visitorVacation);
					log.add(emp.getName() + ": $" + emp.getSalary() +
							" and " + emp.getVacation() + " vacation days");
				}

				log.show();
			}

			// reference
			// http://www.dofactory.com/javascript/visitor-design-pattern
		</script>
	</body>
</html>