@@ -113,3 +113,53 @@ var inherit = (function(){
113113 }
114114})();
115115```
116+ 117+ ## klass
118+ 119+ * some legacy JS libraries/frameworks emulate classes
120+ * usually there's a convention on how to name constructor functions (e.g. init)
121+ * they tend to support classical inheritance
122+ 123+ ## prototypal inheritance
124+ 125+ * modern classless pattern
126+ * no classes, objects inherit from objects
127+ 128+ ``` js
129+ function object (parent ) {
130+ function F () {}
131+ F .prototype = parent;
132+ return new F ();
133+ }
134+ 135+ var parent = { ... }
136+ var child = object (parent);
137+ ```
138+ 139+ * children get parent methods and properties via ``` __proto__ ``` link
140+ * parent can be created via constructor as well (not just literal)
141+ 142+ ## Object.create
143+ 144+ * prototypal inheritance is built-in since ES5
145+ * ``` Object.create(parentObject, ownPropertiesObject) ```
146+ 147+ ## inheritance by copying properties
148+ 149+ ``` js
150+ // shallow copy
151+ function extend (parent , child ) {
152+ var key;
153+ child = child || {};
154+ for (key in parent){
155+ if (parent .hasOwnProperty (key)){
156+ child[key] = parent[key];
157+ }
158+ }
159+ return child;
160+ }
161+ ```
162+ 163+ * shallow copy just copies references of arrays and object
164+ * children can modify parent properties :(
165+ * deep copy is when array elements and object properties are copied as well
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