OOP in JavaScript

it2022-05-09 30

Create a custom object in JavaScript 1function　 Person( name, surname )2{3 this.name = name;4 this.surname = surname;5}67var salvo = new Person( ‘Salvatore’, ‘Vetro’ ); Add a Method in Object 1customeObject.prototype.newMethodName =function;2// Specific case3Person.prototype.Speak = function(){} 例子 1function NewObject() 2{ 3 alert("I am a new object."); 4} 5 6NewObject.prototype = 7{ 8 alert1: function(str){alert(str);}, //new method 910 name: 'As you want', //new property1112 alert2: function(){alert("Bye.");} //new method13};1415var newObject = new NewObject();1617newObject.alert1("Ciao");1819newObject.name;2021newObject.alert2();

每次JavaScript访问一个对象的属性时，将按这个顺序查询：１．如果当前对象的属性是个值，要找的就是这个值了。２．如果当前对象的属性没有值，就查找构造器的所有属性。３．查找直到找到一个合适的属性（有一个值）。原文：If the property has a value assigned to the current (local) object, this is the value to use. If there is no local value, check the value of the property’s prototype of the object’s constructor. Continue up the prototype chain until either a match of the property is found (with a value assigned to it) or the search reaches the native Object object. Therefore, if you change the value of a constructor’s prototype property and you do not override the property value in an instance of that constructor, JavaScript returns the current value of the constructor’s prototype property. Obsever in JavaScript：

Observer 1<html> 2 <head> 3 <script language="javascript"> 4 5 function ArrayList() 6 { 7 this.aList = []; //initialize with an empty array 8 } 9 10 ArrayList.prototype.Count = function() 11 { 12 return this.aList.length; 13 } 14 15 ArrayList.prototype.Add = function( object ) 16 { 17 return this.aList.push( object ); //Object are placed at the end of the array 18 } 19 20 ArrayList.prototype.GetAt = function( index ) //Index must be a number 21 { 22 if( index > -1 && index < this.aList.length ) 23 return this.aList[index]; 24 else 25 return undefined; //Out of bound array, return undefined 26 } 27 28 ArrayList.prototype.Clear = function() 29 { 30 this.aList = []; 31 } 32 33 ArrayList.prototype.RemoveAt = function ( index ) // index must be a number 34 { 35 var m_count = this.aList.length; 36 37 if ( m_count > 0 && index > -1 && index < this.aList.length ) 38 { 39 switch( index ) 40 { 41 case 0: 42 this.aList.shift(); 43 break; 44 case m_count - 1: 45 this.aList.pop(); 46 break; 47 default: 48 var head = this.aList.slice( 0, index ); 49 var tail = this.aList.slice( index + 1 ); 50 this.aList = head.concat( tail ); 51 break; 52 } 53 } 54 } 55 56 ArrayList.prototype.Insert = function ( object, index ) 57 { 58 var m_count = this.aList.length; 59 var m_returnValue = -1; 60 61 if ( index > -1 && index <= m_count ) 62 { 63 switch(index) 64 { 65 case 0: 66 this.aList.unshift(object); 67 m_returnValue = 0; 68 break; 69 case m_count: 70 this.aList.push(object); 71 m_returnValue = m_count; 72 break; 73 default: 74 var head = this.aList.slice(0, index - 1); 75 var tail = this.aList.slice(index); 76 this.aList = this.aList.concat(tail.unshift(object)); 77 m_returnValue = index; 78 break; 79 } 80 } 81 82 return m_returnValue; 83 } 84 85 ArrayList.prototype.IndexOf = function( object, startIndex ) 86 { 87 var m_count = this.aList.length; 88 var m_returnValue = - 1; 89 90 if ( startIndex > -1 && startIndex < m_count ) 91 { 92 var i = startIndex; 93 94 while( i < m_count ) 95 { 96 if ( this.aList[i] == object ) 97 { 98 m_returnValue = i; 99 break;100 }101 102 i++;103 }104 }105 106 return m_returnValue;107 }108 109 110 ArrayList.prototype.LastIndexOf = function( object, startIndex )111 {112 var m_count = this.aList.length;113 var m_returnValue = - 1;114 115 if ( startIndex > -1 && startIndex < m_count ) 116 {117 var i = m_count - 1;118 119 while( i >= startIndex )120 {121 if ( this.aList[i] == object )122 {123 m_returnValue = i;124 break;125 }126 127 i--;128 }129 }130 131 return m_returnValue;132 }133 134 function Observer()135 {136 this.Update = function()137 {138 return;139 }140 }141142143 function Subject()144 {145 this.observers = new ArrayList();146 }147148 Subject.prototype.Notify = function( context )149 {150 var m_count = this.observers.Count();151 152 for( var i = 0; i < m_count; i++ )153 this.observers.GetAt(i).Update( context );154 }155156 Subject.prototype.AddObserver = function( observer )157 {158 if( !observer.Update )159 throw 'Wrong parameter';160161 this.observers.Add( observer );162 }163164 Subject.prototype.RemoveObserver = function( observer )165 {166 if( !observer.Update )167 throw 'Wrong parameter';168 169 this.observers.RemoveAt(this.observers.IndexOf( observer, 0 ));170 }171 172 </script>173 </head>174 <body bgcolor="#ff9900">175 <table width="100%" border="0">176 <tr>177 <td align="center"><INPUT style="color: #ff9900" id="BtnAdd" onclick="AddObserver()" type="button" value='Insert a new "Observer" checkbox'>178 </td>179 </tr>180 <tr>181 <td align="center" width="100%">Observable/Subject<INPUT id="MainCheckBox" type="checkbox" name="MainCheckBox">Checkbox</td>182 </tr>183 <tr>184 <td align="center">185 <div id="MainContainer"></div>186 </td>187 </tr>188 </table>189 <script language="javascript">190 191 function inherits(base, extension)192 {193 for (var property in base)194 {195 try196 {197 extension[property] = base[property];198 }199 catch(warning)200 {201 }202 }203 } 204 205 var cont = document.getElementById('MainContainer');206 207 var mainCheck = document.getElementById('MainCheckBox');208 209 inherits(new Subject(), mainCheck);210 211 mainCheck["onclick"] = new Function("mainCheck.Notify(mainCheck.checked)");212 213 214 function AddObserver()215 {216 var check = document.createElement("INPUT");217 check.type = 'checkbox';218 219 inherits(new Observer(), check)220 221 check.Update = function(value)222 {223 this.checked = value;224 }225 226 mainCheck.AddObserver(check);227 228 cont.appendChild(check);229 }230 231 </script>232 </body>233</html> 学习原文

转载于:https://www.cnblogs.com/nanshouyong326/archive/2006/12/31/608881.html

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