The 'New' Keyword in JavaScript

Transcript

5. var simpleObject = { a: 'a' }; { a: 'a' } simpleObject.toString(); // um, where does this function come from?
7. var simpleObject = { a: 'a' }; { a: 'a', __proto__: { ... toString: function, hasOwnProperty: function, ... } }
8. var Demo = function() { ... }; Demo.prototype.doSomething = function() { ... };
9. var Demo = function() { this.prop = 'text'; }; Demo.prototype.action = function() { alert(this.prop); }; var myDemo = Demo(); myDemo; // undefined myDemo.action() // ERROR window.prop; // 'text'
10. var Demo = function() { this.prop = 'text'; }; Demo.prototype.action = function() { alert(this.prop); }; var myDemo = Demo(); myDemo; // { prop:'a', action:function } window.prop; // undefined myDemo.action(); // alerts "text"
11. var Demo = function() { this.prop = 'text'; }; Demo.prototype.action = function() { alert(this.prop); }; var myDemo = new Demo();
12. var Demo = function() { this.prop = 'text'; }; Demo.prototype.action = function() { alert(this.prop); }; var myDemo = new Demo();
13. • • • • • • • •
14. Object.create(myProtoObject); var obj = Object.create(null); // returns { } obj.toString(); // ERROR
15. var Demo = function() { this.prop = 'text'; }; Demo.prototype.action = function() { alert(this.prop); }; var myDemo = new Demo(); var Demo = { init: function() { this.prop = 'text'; }, action: function() { alert(this.prop); } }; var myDemo = Object.create(Demo); myDemo.init();