added strategy pattern

kazm8 · Dec 16, 2011 · 8197035 · 8197035
1 parent cdfc5a5
commit 8197035
Showing 1 changed file with 108 additions and 0 deletions.
diff --git a/design-patterns/strategy.html b/design-patterns/strategy.html
@@ -0,0 +1,108 @@
+<!doctype html>
+<html lang="en">
+<head>
+<title>JavaScript Patterns</title>
+<meta charset="utf-8">
+</head>
+<body>
+<script>
+var validator = {
+
+  // all available checks
+  types: {},
+
+  // error messages in the current
+  // validation session
+  messages: [],
+
+  // current validation config
+  // name: validation type
+  config: {},
+
+  // the interface method
+  // 'data' is key => value pairs
+  validate: function (data) {
+
+    var i, msg, type, checker, result_ok;
+
+    // reset all messages
+    this.messages = [];
+
+    for (i in data) {
+
+      if (data.hasOwnProperty(i)) {
+
+        type = this.config[i];
+        checker = this.types[type];
+
+        if (!type) {
+          continue; // no need to validate
+        }
+        if (!checker) { // uh-oh
+          throw {
+            name: "ValidationError",
+            message: "No handler to validate type " + type
+          };
+        }
+
+        result_ok = checker.validate(data[i]);
+        if (!result_ok) {
+          msg = "Invalid value for *" + i + "*, " + checker.instructions;
+          this.messages.push(msg);
+        }
+      }
+    }
+    return this.hasErrors();
+  },
+
+  // helper
+  hasErrors: function () {
+    return this.messages.length !== 0;
+  }
+};
+
+// checks for non-empty values
+validator.types.isNonEmpty = {
+  validate: function (value) {
+    return value !== "";
+  },
+  instructions: "the value cannot be empty"
+};
+
+// checks if a value is a number
+validator.types.isNumber = {
+  validate: function (value) {
+    return !isNaN(value);
+  },
+  instructions: "the value can only be a valid number, e.g. 1, 3.14 or 2010"
+};
+
+// checks if the value contains only letters and numbers
+validator.types.isAlphaNum = {
+  validate: function (value) {
+    return !/[^a-z0-9]/i.test(value);
+  },
+  instructions: "the value can only contain characters and numbers, no special symbols"
+};
+
+var data = {
+  first_name: "Super",
+  last_name: "Man",
+  age: "unknown",
+  username: "o_O"
+};
+
+validator.config = {
+  first_name: 'isNonEmpty',
+  age: 'isNumber',
+  username: 'isAlphaNum'
+};
+
+validator.validate(data);
+
+if (validator.hasErrors()) {
+  console.log(validator.messages.join("\n"));
+}
+</script>
+</body>
+</html>