JavaScript Object Oriented Programming Cheat Sheet

Editor's Notes

• #5: //Declaration object references var obj_inst_1, obj_inst_2; //Use the Object constructor in conjunction with the new operator to //instantiate a new object and assign the reference to obj_inst_1 obj_inst_1 = new Object(); //In JavaScript object properties and methods can be added on the fly obj_inst_1.prop = "Added on the fly"; obj_inst_1.func = function() {return this.prop + "!";}; toFiddleResult(obj_inst_1.func()); //Object literal, an alternative way to instantiate Javascript objects obj_inst_2 = { prop: "Added as part of the object literal", func: function() {return this.prop + "!";} }; toFiddleResult(obj_inst_2.func()); //There is no need to instantiate objects without constructors, i.e. //the global object, Math & JSON var global = this; //In top level code this refers to the global object toFiddleResult("Is 42 a finite number? " + global.isFinite(42)); toFiddleResult("The number u03c0 = " + Math.PI); //Primitive wrapper objects are created automatically when needed var str = "u00a9 Hans de Rooij"; toFiddleResult(str.substring(2, 6) + " wrote this code"); //Function for displaying code results in the JSFiddle results pane function toFiddleResult(str) { //Reference to document node containing fiddle results var result_div = document.getElementById("fiddle_result"); //Fiddle results are listed in pre tags var add_pre = document.createElement("pre"); add_pre.appendChild(document.createTextNode(str)); result_div.appendChild(add_pre); }