JavaScript Learning notes (i)

= = = "2 = with 3 =" ===var result1= ("55" ==55); -Truevar result2= ("55" ===55); ->falsealert (result1+ "; "+result2");//=====for In======for (var propname in window) {document.write (propname);d ocument.write ("</br>");} The return statement of the = = function =====function sum (A, b) {return A+b;alert ("Hello"),//return statements will not be executed}document.write (sum (2,3)); function Sayhi (name,message) {return;//Output Undefinedalert ("Heloo");//The same Heloo will not output}document.write (Sayhi ("Me")); document.write ("<br/>"), function Sayhi () {document.write ("Hello" +arguments[0]+ "," +arguments[1]);} Sayhi ("He", "said"),//========arguments with parameters =====function Doadd (num1,num2) {Arguments[1]=10;alert (arguments[0]+num2 );} Doadd (11,2); 21DOADD (11); ->nan, only one parameter is passed in, and the value set by arguments[1] is not reflected in the named parameter.   Doadd (); ->nan, a named parameter that does not pass a value, is automatically assigned the undefined value. = = = function with no return statement ======/*function Add (A, B) {var result = a+b;} Alert (Add (2,3)); ->undefined, a function that does not specify a return value returns a special undefined value. *///======object======/*var person = new Object ();p erson.name = "Nicolas"; alert (pErson.name); ->nicolas;var name= "Nicolas"; name.age = 27;alert (name.age); ->undefined, you cannot add a property to a base type value. *///======== basic type and reference type ======function Addten (num) {num = 10;return num;} var count = 20;var result = Addten (count); alert (count); ->20alert (result); ->30function setName (obj) {obj.name = "Nicolas";} var person = new Object (), setName (person);d ocument.write (person.name); ->nicolasdocument.write ("<br/>"), function setName1 (obj) {obj.name = "Angle"; obj = new Object (); obj.name = " Greg ";} var person1 = new Object (); setName1 (Person1);d ocument.write (person1.name); ->angle, indicating that the JavaScript object parameter is a value pass alert (Person1 instanceof object);//========json========/* * Json.stringify () Serializes a JavaScript object into a JSON string * Any property with a value of undefined will also be skipped * */var book = {title: "Professional JavaScript", authors:[" Nicholas c. Zakas "],edition:3,year:2011,denote:undefined};var jsontext = json.stringify (book); alert (jsontext); var CopyBook = Json.parse (jsontext); Alert (copybook["year"]);/* * Filter Results * Json.striNgfy (array,["param1", "param2"]) */var JsonText1 = json.stringify (book,["title", "edition"]);d Ocument.write ( JSONTEXT1);/* * String indent *json.stringify (value [, Replacer] [, space]) *//*var jsonText2 = json.stringify (book,null,4);//Indent 4 A space alert (JSONTEXT2);/* * ToJson */var Book1 = {title: "Professional JavaScript", authors:["Nicholas c. Zakas"],edition:3, Year:2011,tojson:function () {return this;}}; var jsonText3 = json.stringify (BOOK1); alert (JSONTEXT3);

　　

JavaScript Learning notes (i)