Getting Started with JavaScript learning notes---

Both 1.JavaScript statements and JavaScript variables are case-sensitive.

2. Re-declare JavaScript variables

If you re-declare a JavaScript variable, the value of the variable is not lost:

After the following two statements are executed, the value of the variable carname remains "Volvo":

var carname= "Volvo"; var carname;


3.JavaScript has a dynamic type . This means that the same variables can be used for different types:
JavaScript Data type -----string, Number, Boolean, array, object, Null, Undefined

4. Array:(in brackets)

var cars=["Audi", "BMW", "Volvo";

5.JavaScript Object (curly braces)

var person={firstname: "Bill", LastName: "Gates", id:5566};

name=person.lastname;name=person["LastName"];

6. Creating JavaScript Objects

Person=new Object ();p erson.firstname= "Bill";p erson.lastname= "Gates";p erson.age=56;person.eyecolor= "Blue";
7. If you add a number to a string, the result becomes a string

8.Switch

Switch (n) {Case 1:  Execute code block 1  break;case 2:  Execute code block 2  break;default:  N code that executes when different from 1 and 2

9.for/in Cycle

exception

An exception can be a JavaScript string, a number, a logical value, or an object. e.g.

<script>function myFunction () {try  {  var X=document.getelementbyid ("Demo"). Value;  if (x== "")    throw "empty";  if (IsNaN (x)) throw "not a number";  if (x>10)     throw "too high";  if (x<5)      throw "too low";  } catch (Err)  {  var Y=document.getelementbyid ("mess");  Y.innerhtml= "Error:" + Err + ".";  }} </script>
　　
11.e-mail Verification
functionValidate_email (field,alerttxt) { with(field) {apos=value.indexof ("@") Dotpos=value.lastindexof (".")if(apos<1| | Dotpos-apos<2) {alert (alerttxt);return false}Else{return true}}}functionValidate_form (thisform) { with(thisform) {if(Validate_email (email, "Not a valid e-mail address!") ==false) {email.focus ();return false}}}</script>Email:<input type= "text" name= "email" size= "><input type=" Submit "value=" Submit "> </form></body >














Getting Started with JavaScript learning notes---