inhert.js

var B = function(b){this.b = b};
var F = function(f){this.f = f};

F.prototype = new B(2);
F.prototype.addF = function(){console.log(‘f’)};
B.prototype.addB = function(){console.log(‘b’)};
B.prototype.constructor = F;

var f = new F(1);

var B = function(b){this.b = b};
B.prototype.addB = function(){console.log(‘B’)};

var S = function(s){this.s = s;}
var T = function(){}

T.prototype = B.prototype;
S.prototype = new T();
S.prototype.addS = function(){console.log(‘S’)};

var s = new S(1);

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sharif

Inheritance
The Original Way
function BaseClass() {}
BaseClass.prototype.aMethod = function() {}
function SubClass() {}
SubClass.prototype = new BaseClass();
● Problem is we have to create a new instance of
BaseClass before we have even created a our SubClass
instance
● What if we need to pass parameters to BaseClass?
These should be passed to our new SubClass which
then calls the BaseClass constructor (super)

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Lasse Reichstein Nielsen Method
Crockford claims it as his own
function BaseClass() {}
BaseClass.prototype.aMethod = function() {}
function SubClass() {}
var TmpFn = function() {};
TmpFn.prototype = BaseClass.prototype;
SubClass.prototype = new TmpFn();

● Avoids calling new on the BaseClass
● But, remember when functions are declared, ECMA script
automatically creates a prototype object with a constructor
property pointing back to the function… One last step:

SubClass.prototype.constructor = SubClass
//Otherwise it will inherit the constructor
from BaseClass