Prototype usage guide base.js_prototype

base.js contains the following content Creation and inheritance of classes: Class.create(): Create a class, such as person=Class.create() Object.extend(destination, source): Copy the method properties in the source to the destination (use for property in source). It should be noted that except for the basic types (Number, Boolean) in javascript, they are all reference types, so this kind of copy is generally just copying the reference, destination and source still point to the same method or object attribute (function array object). In object-oriented programming, a new class is generally created through Class.create. If this class inherits from a class, Object.extend(class.prototype, parentClass.prototype) or Object.extend(class.prototype, aparentClassInstance)
Extension of Object constructor: Object is the constructor of other object instances (var a=new Object()), and also all The parent class of other classes directly extends Object (note that it does not extend Object.prototype, extending Object.prototype is equivalent to adding an instance method), which is equivalent to adding a static method Object.inspect(object) to the Object class: calling the inspect of object (if defined ) or toString method, returns the string representation of an object. Object.keys(object): Returns an array consisting of all properties and method names of an object, such as Object.keys(document.body) Object.values(object): Returns An array composed of the values ​​of all properties and methods of an object, such as Object.values(docuement) Object.clone(object): Returns the clone version of an object. In fact, it executes the Object.extent method to copy the method attributes in the object to an in the new object, and then return this object
Function bonding: defines two methods of the Function object, bind and bindAsEventListener. These two methods are two methods of one function. For java and c# Programmers may be surprised to see this, because in their view, a function is just a program statement organization structure ---> How come there are methods and they can be expanded? This is also a very powerful feature of scripting languages ​​such as JavaScript compared to Java. A function is also an object, and the function name is the name of the object. As long as you want, you can also use new Function(...) to define the function, so for The function definition method is very normal. The main function of these two functions is to solve the reference problem of this in object-oriented programming using JavaScript. In javasctipt, the this keyword always points to the object that calls the function. Or point to the object specified using the call and apply methods (you can Google it yourself for specific knowledge in this area. The following series of introductions to prototype also assume that the reader is familiar with the JavaScript language. If you are not familiar with it, you can find this book javascript Take a look at the authoritative guide book ) To understand this problem, you must first understand that always points to this problem, that is, the keyword this is quite special and cannot be treated as a general variable name. One of the most common mistakes is to use this in a call to a returning function, such as return function(){this.aMethod()}. When you call the returned anonymous method next time, the content of this this reference will point to the calling method. The object of the function. Remember that this is a keyword, not a variable name, and will not produce a closure. is an extension of Number (note that num can also be regarded as an object. In fact, the system automatically packages it into Number object): toColorPart: Convert the number into a hexadecimal value that can be used to represent color: for example 7.toColorPart()=>"07", 28.toColorPart()=>"1C" succ: return num , but does not change the value of num itself, it is actually return this+1 times: calling a function in turn from 0 to this number, such as function a(n){document.write(n)}, 10.times(a), will be displayed 012345678910, Note that a function is also an object, and there is no real difference from other objects Try object:
The Try object provides a very interesting function, first look at the following code: var Ajax = { getTransport: function() { return Try.these( function() {return new XMLHttpRequest()}, function() {return new ActiveXObject('Msxml2.XMLHTTP')}, function() {return new ActiveXObject('Microsoft.XMLHTTP ')} ) || false; } } The Try object provides a method these, which accepts a parameter list of function type, and then executes these functions in turn. When one of the functions does not generate an error, it stops execution and returns this You can experience the value returned by the function slowly PeriodicalExecuter (periodic executor) object This object is a simple encapsulation of the setInterval method. The usage method is as follows var a=new PeriodicalExecuter(callback, frequency) //callback : Function name to be executed frequency: Time interval for each execution a.stop()