[추천]자 바스 크 립 트 대상 기술 기초 강좌

 
var emptyObject1 = {}; //      
var emptyObject2 = new Object(); //      
var person = {"name":"sdcyst", 
"age":18, 
"sex":"male"}; //            person 
alert(person.name); //sdcyst 
alert(person["age"]); //18 

 
var person = {}; 
person.name = "sdcyst"; 
person["age"] = 18; 
alert(person.name + "__" + person.age); //sdcyst__18 
var _person = {name:"balala","age":23}; //        ,              (name), 
//            .      []        
alert(_person["name"] + "__" + person.age); //balala__23 
alert(_person[name]); //undefinied 
var person = {}; 
person.name = "sdcyst"; 
person["age"] = 18; 
alert(person.name + "__" + person.age); //sdcyst__18 
var _person = {name:"balala","age":23}; //        ,              (name), 
//            .      []        
alert(_person["name"] + "__" + person.age); //balala__23 
alert(_person[name]); //undefinied 

 
var name = {"name1":"NAME1","name2":"NAME2","name3":"NAME3","name4":"NAME4"}; 
var namestring = ""; 
for(var props in name) { //  name         
namestring += name[props]; 
} 
alert(namestring); //NAME1NAME2NAME3NAME4 

namestring = ""; 
for(var i=0; i<4; i++) { 
namestring += name["name"+(i+1)]; 
} 
alert(namestring); //NAME1NAME2NAME3NAME4 

 
var name = {"name1":"NAME1","name2":"NAME2","name3":"NAME3","name4":"NAME4"}; 
var namestring = ""; 
for(var props in name) { //  name         
namestring += name[props]; 
} 
alert(namestring); //NAME1NAME2NAME3NAME4 

delete name.name1; //  name1   
delete name["name3"]; //  name3   
namestring = ""; 
for(var props in name) { //  name         
namestring += name[props]; 
} 
alert(namestring); //NAME2NAME4 

alert("name1" in name); //false 
alert("name4" in name); //true 

 
var date = new Date(); 
alert(date.constructor); //Date 
alert(date.constructor == "Date"); //false 
alert(date.constructor == Date); //true 

 
var array1 = []; //      
var array2 = new Array(); //      
array1 = [1,"s",[3,4],{"name1":"NAME1"}]; // 
alert(array1[2][1]); //4            
alert(array1[3].name1); //NAME1          
alert(array1[8]); //undefined 
array2 = [,,]; //          ,          undefined 
alert(array2.length); //3 
alert(array2[1]); //undefined 
var array1 = []; //      
var array2 = new Array(); //      
array1 = [1,"s",[3,4],{"name1":"NAME1"}]; // 
alert(array1[2][1]); //4            
alert(array1[3].name1); //NAME1          
alert(array1[8]); //undefined 
array2 = [,,]; //          ,          undefined 
alert(array2.length); //3 
alert(array2[1]); //undefined 

 
var array = new Array(10); 
alert(array.length); //10 
alert(array[4]); //undefined 
array[100] = "100th"; //            ,   10-99        undefined 
alert(array.length); //101 
alert(array[87]); //undefined 
var array = new Array(10); 
alert(array.length); //10 
alert(array[4]); //undefined 
array[100] = "100th"; //            ,   10-99        undefined 
alert(array.length); //101 
alert(array[87]); //undefined 

 
var array = new Array("n1","n2","n3","n4","n5"); //        
var astring = ""; 
for(var i=0; i<array.length; i++) { //       
astring += array[i]; 
} 
alert(astring); //n1n2n3n4n5 
delete array[3]; //         
alert(array.length + "_" + array[3]) //5_undefined 

array.length = 3; //        
alert(array[3]); //undefined 
array.length = 8; //        
alert(array[4]); //undefined 
var array = new Array("n1","n2","n3","n4","n5"); //        
var astring = ""; 
for(var i=0; i<array.length; i++) { //       
astring += array[i]; 
} 
alert(astring); //n1n2n3n4n5 
delete array[3]; //         
alert(array.length + "_" + array[3]) //5_undefined 

array.length = 3; //        
alert(array[3]); //undefined 
array.length = 8; //        
alert(array[4]); //undefined 

 
var array = new Array("no1","no2"); 
array["po"] = "props1"; 
alert(array.length); //2 
//      ,array[0] array["0"]      (?   ,     ) 
alert(array[0] + "_" + array["1"] + "_" + array.po);//no1_no2_props1 

 
function f(x) {........} 
var f = function(x) {......} 

 
function myprint(s1,s2,s3) { 
alert(s1+"_"+s2+"_"+s3); 
} 
myprint(); //undefined_undefined_undefined 
myprint("string1","string2"); //string1_string2_undefined 
myprint("string1","string2","string3","string4"); //string1_string2_string3 
function myprint(s1,s2,s3) { 
alert(s1+"_"+s2+"_"+s3); 
} 
myprint(); //undefined_undefined_undefined 
myprint("string1","string2"); //string1_string2_undefined 
myprint("string1","string2","string3","string4"); //string1_string2_string3 

 
function myprint(s1,person) { 
var defaultperson = { //  person   
"name":"name1", 
"age":18, 
"sex":"female" 
}; 
if(!s1) { //s1      
alert("s1 must be input!"); 
return false; 
} 
person = person || defaultperson; //  person     
alert(s1+"_"+person.name+":"+person.age+":"+person.sex); 
}; 

myprint(); //s1 must be input! 
myprint("s1"); //s1_name1:18:female 
myprint("s1",{"name":"sdcyst","age":23,"sex":"male"}); //s1_sdcyst:23:male 
function myprint(s1,person) { 
var defaultperson = { //  person   
"name":"name1", 
"age":18, 
"sex":"female" 
}; 
if(!s1) { //s1      
alert("s1 must be input!"); 
return false; 
} 
person = person || defaultperson; //  person     
alert(s1+"_"+person.name+":"+person.age+":"+person.sex); 
}; 

myprint(); //s1 must be input! 
myprint("s1"); //s1_name1:18:female 
myprint("s1",{"name":"sdcyst","age":23,"sex":"male"}); //s1_sdcyst:23:male 

 
function myargs() { 
alert(arguments.length); 
alert(arguments[0]); 
} 
myargs(); //0 --- undefined 
myargs("1",[1,2]); //2 --- 1 
function myargs() { 
alert(arguments.length); 
alert(arguments[0]); 
} 
myargs(); //0 --- undefined 
myargs("1",[1,2]); //2 --- 1 Arguments     callee  ,     Arguments       .                   . 

 
function(x) { 
if (x <= 1) return 1; 
return x * arguments.callee(x-1); 
} (section8.2) 
function(x) { 
if (x <= 1) return 1; 
return x * arguments.callee(x-1); 
} (section8.2) 

 
var obj = {f0:function(){alert("f0");}}; //         
function f1() {alert("f1");} 
obj.f1 = f1; //        

obj.f0(); //f0 f0 obj    
obj.f1(); //f1 f1 obj    
f1(); //f1 f1        ,       
f0(); //f0   obj   ,          
var obj = {f0:function(){alert("f0");}}; //         
function f1() {alert("f1");} 
obj.f1 = f1; //        

obj.f0(); //f0 f0 obj    
obj.f1(); //f1 f1 obj    
f1(); //f1 f1        ,       
f0(); //f0   obj   ,          

 
var obj = {"name":"NAME","sex":"female"}; 
obj.print = function() { //        
alert(this.name + "_" + this["sex"]); 
}; 
obj.print(); //NAME_female 
obj.sex = "male"; 
obj.print(); //NAME_male 
var obj = {"name":"NAME","sex":"female"}; 
obj.print = function() { //        
alert(this.name + "_" + this["sex"]); 
}; 
obj.print(); //NAME_female 
obj.sex = "male"; 
obj.print(); //NAME_male 

 
var person = {name:"defaultname", 
setName:function(s){ 
this.name = s; 
}, 
"printName":function(){ 
alert(this.name); 
}} 
person.printName(); //defaultname 
person.setName("newName"); 
person.printName(); //newName 
var person = {name:"defaultname", 
setName:function(s){ 
this.name = s; 
}, 
"printName":function(){ 
alert(this.name); 
}} 
person.printName(); //defaultname 
person.setName("newName"); 
person.printName(); //newName