How to declare objects in js and some usage examples of arrays_Basic knowledge

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<script> <BR>//Define a printing function<BR>var $=function(str) { <BR>document.write(str); <BR>document.write("<br/>"); <BR>} <BR>//Define the print array function<BR>var _=function(arr ){ <BR>for(var tmp in arr) <BR>{ <BR>$(arr[tmp]); <BR>} <BR>} <BR>//Define a student object <BR>var stu= new Object(); <br><br>//Declare properties and behaviors <BR>stu.id=16; <BR>stu.name='Lamp Coin'; <BR>stu.age=function(){ <BR>return this.id; <BR>} <br><br>//Print student information <BR>$(stu.id); <BR>$(stu.name); <BR>$(stu. age()); //Add brackets when calling <br><br>stu.sex='female'; //Add new attributes<BR>$(stu.sex); //Print the newly added attributes<br><br>//Option 2: <BR>function Student(id,name) <BR>{ <BR>this.id=id; <BR>this.name=name; <BR>this.getAge=function( ){ <BR>return this.id; <BR>} <br><br>} <br><br>//Use <BR>var stu2=new Student(1,'Yangton'); <BR> $(stu2.id); <BR>$(stu2.name); <BR>$(stu2.getAge()); <BR>//Define another attribute <BR>stu2.sex='pseudo-girl'; <BR>$(stu2.sex); <BR>//How does dynamic language cross domains? <BR>Student.prototype.address="Afghanistan"; <BR>$(stu2.address); <BR>$("stu2_1 begin..."); <BR>var stu2_1 =new Student(1,'杨Dayton'); <BR>$(stu2_1.id); <BR>$(stu2_1.name); <BR>$(stu2_1.getAge()); <BR>$(stu2_1.sex); <BR>$ (stu2_1.address); //Cross-domain access, b object accesses the attributes of a object<BR>//In the definition<BR>$("stu2_1 end..."); <br><br>//Option 3 ：json <BR>var stu3={id:1,name:'Mao Yanyan',getName:function(){return this.name;}}; <BR>$(stu3.id); <BR>$(stu3 .name); <BR>$(stu3.getName()); <br><br>//var stu2 <br><br>//Many functions in js have the same name as functions in java<BR>var str1= new String("abcd") <BR>var str2="asdf"; <BR>$(str1.indexOf('c')); <BR>$(str1.charAt(3)); <BR>$ ( str2.charAt(3)); <BR>$("absdf".substring(2,4)); <br><br>var day=new Date(); <BR>$(day.getYear()) ; <BR>$(day.toLocaleString()); <br><br><BR>//Let’s talk about arrays again<BR>var arr1=new Array(3); <BR>arr1[0]=10; <BR>arr1[1]=20; <BR>arr1[2]=3; <BR>_(arr1); <BR>arr1[3]=4; <BR>// <BR>_(arr1); <br><br>//Array 2 <BR>var arr2=new Array(234,345,2354,2134,234); <BR>_(arr2); <br><br>//Array 3 <BR>var arr3=new Array(); <BR>arr3[0]=10; <BR>arr3[1]=20; <BR>arr3[2]=3; <BR>_(arr3); <br><br>//Array 4. Recommended writing method <BR>var arr4=[]; <BR>arr4[0]=10; <BR>arr4[1]=20; <BR>arr4[2]=3; <BR> _(arr4); <br><br>//Array 5. Recommended writing method <BR>var arr5=[3254,43,532,45,2345]; <BR>_(arr5); <br><br>function add (i,j){ <BR>return i j; <BR>} <br><br>function add(i,j,k){ <BR>return i j k; <BR>} <br><br>$( add(1,2));//Automatic recognition of the number of parameters<br><br>var Person=function(id,name) <BR>{ <BR>this.id=id;//public <BR>this .name=name;//public <BR>var i=1;//private <BR>function test(){//private <BR>alert('asdf'); <BR>} <BR>this.t =function()//public <BR>{ <BR>return 1; <BR>} <BR>} <BR>var p=new Person(1,"陈新"); <BR>$(p.id ); <BR>$(p.name); <BR>$(p.t());//Normal access<BR>$(p.test()); //Cannot access<BR></script>