I know it’s already been answered but, there’s a better way to do inheritance. Calling a constructor just for the purpose of inheritance is not desirable. One of the undesired effects is.<\/p>\n
function Base() {this.a = \"A\"}\nfunction Child() {this.b = \"B\"};\n\nChild.prototype = new Base();\n<\/code><\/pre>\nNow You’ve added property “a” to the prototype of Child that you didn’t intend to.<\/p>\n
Here’s the right way (I didn’t invent this, Ext-JS and other libs use this)<\/p>\n
\/\/ This is used to avoid calling a base class's constructor just to setup inheritance.\nfunction SurrogateCtor() {}\n\n\/**\n * Sets a contructor to inherit from another constructor\n *\/\nfunction extend(BaseCtor, DerivedCtor) {\n \/\/ Copy the prototype to the surrogate constructor\n SurrogateCtor.prototype = BaseCtor.prototype;\n \/\/ this sets up the inheritance chain\n DerivedCtor.prototype = new SurrogateCtor();\n \/\/ Fix the constructor property, otherwise it would point to the BaseCtor\n DerivedCtor.prototype.constructor = DerivedCtor;\n \/\/ Might as well add a property to the constructor to \n \/\/ allow for simpler calling of base class's method\n DerivedCtor.superclass = BaseCtor;\n}\n\nfunction Base() {\n this.a = \"A\";\n}\n\nBase.prototype.getA = function() {return this.a}\n\nfunction Derived() {\n Derived.superclass.call(this); \/\/ No need to reference the base class by name\n this.b = \"B\";\n}\n\nextend(Base, Derived);\n\/\/ Have to set methods on the prototype after the call to extend\n\/\/ otherwise the prototype is overridden;\nDerived.prototype.getB = function(){return this.b};\nvar obj = new Derived();\n<\/code><\/pre>\nAn even easier way is to add a third parameter to extend where you specify the method of the derived class so that you don’t have to call extend and then add methods to the prototype<\/p>\n
extend(BaseCtor, DerivedCtor, {\n getB: function() {return this.b}\n});\n<\/code><\/pre>\nThen there are many other things you could do for syntactic sugar.<\/p>\n
Blogged about it: http:\/\/js-bits.blogspot.com\/2010\/08\/javascript-inheritance-done-right.html<\/p>\n
Originally posted 2013-11-09 22:53:28. <\/small><\/p>","protected":false},"excerpt":{"rendered":"
I know it’s already been answered but, there’s a better way to do inheritance. Calling a constructor just for the purpose of inheritance is not desirable. One of the undesired effects is. function Base() {this.a = “A”} function Child() {this.b = “B”}; Child.prototype = new Base(); Now You’ve added property “a” to the prototype of […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-886","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/886","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/comments?post=886"}],"version-history":[{"count":0,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/886\/revisions"}],"wp:attachment":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/media?parent=886"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/categories?post=886"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/tags?post=886"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}