JavaScript--Note

1.  Fllow control statements

var a = 21;

  switch(a)

{

              case a == 1 : alert("first ");break;

default: alert("error");

}

2. Input/output

var a = prompt("test");

alert(a);

3. loops

var a=1; do

{

document.write("/r/n");

  document.write(a); a++;

}while (a<100)

4. Ways to include script in html

< html >

< head >< title > Four Standard Ways to include script in html title >

< script type ="text/javascript" src = "2way.js" />

 

head >

< body >

< script type ="text/javascript">

    function a()

    {

        alert("1 way to include script" );

    }

script >

< input value = "1 way to include script"   id ="1 way to include script" type ="button" value ="button" onclick = "a()"/>

< input value = "2 way to include script"   id ="2 way to include script" type ="button" value ="button" onclick = "b()"/>

< a href = "#" onclick = "javascript: alert('Brcue.Lun');return false;"> br a >

body >

html >

Regular Expression

var a= new RegExp("New" );

var b = "BruceNew" ;

alert(b);

alert(b.replace(a,"old" ));  ---- à Bruceold

6 . Boleans

var inLatinOctal = "/102";

var inLatinHex = "/x42"

var inUnicode = "/u0042";

 

7. Boleans

if(b)

{

    alert("true");

}else

{

    alert("false");

}

var b = 1; --------- à    true;

var b = -1; --------- à    true;

var b = 0; --------- à    false;

var b = false; --------- à    false;

var b = null; --------- à false

var b = true; --------- à    true;

 

8. Create Object

var testObject = new Object();

testObject.id = 1234;

testObject.name = "Bruce.Lun";

alert(testObject.id);

alert(testObject.name);

9. Conversion rules for primitive types

Table 3-5: Result of Conversion to a Boolean
Type	Converted to Boolean
Undefined	false
Null	false
Number	false if 0 or NaN, else true
String	false if string length is 0, else true
Other object	true

 

Table 3-6: Result of Converting to a Number
Type	Converted to Number
Undefined	NaN
Null	0
Boolean	1 if true , 0 if false
String	The numeric value of the string if it looks like a number, else NaN
Other object	NaN

 

Table 3-7: Result of Converting to a String
Type	Converted to a String
Undefined	"Undefined "
Null	"Null"
Boolean	"True" if true , "false" if false
Number	"NaN", "0", or the string representation of the numeric value
Other object	Value of object's toString() method if it exists, else "undefined "

 

10. Promotion of Primitive Data to Objects

var a = "Bruce.Lun";

alert(a.toUpperCase());

alert(a.toLowerCase());// as same as  "Bruce.Lun".toLowerCase()

 

11. javascript five primitive data types

number, string, Boolean, undefined , and null

 

12. & | ^  operator

var a = 5; 0000 0101   AND

var b = 2; 0000 0010

alert(a&b);  -- à output 0;

 

var a = 5;  OR

var b = 2;

alert(a|b); -- à output 7;

 

var a = 5;   XOR

var b = 3;

alert(a^b);  -- à output 6;

 

13. precedence

Precedence	Associativity	Operator	Operator Meaning
Highest: 0	Left to right	.	Object property access
0	Left to right	[ ]	Array access
0	Left to right	( )	Grouping or function or method call
1	Right to left	++	Increment
1	Right to left	--	Decrement
1	Right to left	–	Negation
1	Right to left	~	Bitwise NOT
1	Right to left	!	Logical NOT
1	Right to left	delete	Remove object property or array value
1	Right to left	new	Create object
1	Right to left	typeof	Determine type
1	Right to left	void	Suppress expression evaluation
2	Left to right	* , / , %	Multiplication, division, modulus
3	Left to right	+ , –	Addition, subtraction
3	Left to right	+	String concatenation
4	Left to right	>>	Bitwise right-shift with sign
4	Left to right	>>>	Bitwise right-shift with zero fill
4	Left to right	<<	Bitwise left-shift
5	Left to right	>, >=	Greater than, greater than or equal to
5	Left to right	<, <=	Less than, less than or equal to
6	Left to right	==	Equality
6	Left to right	!=	Inequality
6	Left to right	===	Equality with type checking (Identity)
6	Left to right	!==	Inequality with type checking (Non-identity)
7	Left to right	&	Bitwise AND
8	Left to right	^	Bitwise XOR
9	Left to right	|	Bitwise OR
10	Left to right	&&	Logical AND
11	Left to right	||	Logical OR
12	Right to left	? :	Conditional
13	Right to left	=	Assignment
13	Right to left	*= , /= , %= , += , –= , <<= , >>= , >>>= , &= , ^= , |=	Assignment in conjunction with preceding operator
Lowest: 14	Left to right	,	Multiple evaluation

 

 

14. local function

function a()

{

    function b()

    {

        return 2;

    }

    alert(b());

}

a();

 

15. Function as Objects

var test = new Function("alert('HelloWorld');");  // Note: F is Capitalized

test();

var test2 = test;  // copy to another object 

test2();

var test = new Function("arg","alert('Hello/t'+arg);"); //arg is a argment

test("Bruce");   ---------- à output Hello Bruce

General Syntax :

Var functionName = new Function(“argment 1”,…….”argment n” ,”statements for function body.”);

 

16.Function literals

var test = function(name){alert(name);}

test("Bruce");

 

17.simple class

 

function AutoMan(comm)

{

    this.name = comm;

    this.kick = function (){alert(this.name);}

    this.hit = new Function("alert('Dont hit you brother');");

}

var a = new AutoMan("Ha~ Look this......");

a.kick();

a.hit();

 

18. Advanced  Parameter Passing

function adv()

{

    alert(adv.arguments.length); --- à output 3

    alert(adv.arguments[0]); ---- à output 1

}

adv(1,2,3);

 

19. 　Ｒｅｃｕｒｓｉｏｎ

function   jc(varNumber)

{

document.write(varNumber);

document.write("
");

 

    if(varNumber<0)return -1;

    if(varNumber==0)return 1;

document.write(varNumber*jc(varNumber - 1));

document.write("
");

    return varNumber*jc(varNumber - 1);

}

document.write(jc(5));

document.write("
");

 

20. 　ＪＳ　ｃｏｐｙ　

var stu = { name:"a" , id:"19880904" , age: "20" ,call:function(){alert(this.name);} };

stu.call();

var b = stu;

b.call();

(function(){alert("Pa  you  died ~");})(); 　    ＝

var a = function(){alert("Pa  you  died ~");}  +

a();

---------------(function(m){alert(m);})(1);   //parameter OK

 

21. clone object

var stu = { name:"a" , id:"19880904" , age: "20" ,call:function(){alert(this.name);} };

stu.call();

var b = new Object();

for(var a in stu)

{

    b[a] = stu[a];

}

 

stu.call = function(){alert("Test");};   //set alert value : Test

 

b.call();     // alert value : a