Giáo trình về Javascript

JAVASCRIPT

Baøi 1: TOÅNG QUAN VEÀ JAVASCRIPT.

1. Ñaëc tính cuûa ngoân ngöõ Javascript:

avascript laø moät ngoân ngöõ thoâng dòch (interpreter), chöông trình nguoàn cuûa noù ñöôïc nhuùng

J_{(embedded) hoaëc tích hôïp (integated) vaøo taäp tin HTML chuaån. Khi file ñöôïc load trong}

Browser (coù support cho JavaScript), Browser seõ thoâng dòch caùc Script vaø thöïc hieän caùc coâng vieäc

xaùc ñònh. Chöông trình nguoàn JavaScript ñöôïc thoâng dòch trong trang HTML sau khi toaøn boä trang

ñöôïc load nhöng tröôùc khi trang ñöôïc hieån thò.

Javascript laø moät ngoân ngöõ coù ñaëc tính:

•

Ñôn giaûn.

Ñoäng (Dynamic).

Höôùng ñoái töôïng (Object Oriented).

2. Ngoân ngöõ JavaScript:

Moät trong nhöõng ñaëc tính quan troïng cuûa ngoân ngöõ JavaScript laø khaû naêng taïo vaø söû duïng caùc ñoái

töôïng (Object). Caùc Object naøy cho pheùp ngöôøi laäp trình söû duïng ñeå phaùt trieån öùng duïng.

Trong JavaScript ,caùc Object ñöôïc nhìn theo 2 khía caïnh:

a. Caùc Object ñaõ toàn taïi.

b. Caùc Object do ngöôøi laäp trình xaây döïng.

Trong caùc Object ñaõ toàn taïi ñöôïc chia thaønh 2 kieåu:

a. Caùc Object cuûa JavaScript (JavaScript Built-in Object).

b. Caùc ñoái töôïng ñöôïc cung caáp bôûi moâi tröôøng Netscape.

3. Built-in Object trong JavaScript:

JavaScript cung caáp 1 boä caùc Built-in Object ñeå cung caáp caùc thoâng tin veà söï hieän haønh cuûa caùc

ñoái töôïng ñöôïc load trong trang Web vaø noäi dung cuûa noù.Caùc ñoái töôïng naøy bao goàm caùc phöông

phaùp (Method) laøm vieäc vôùi caùc thuoäc tính (Properties) cuûa noù.

4. Caùc ñoái töôïng ñöôïc cung caáp bôûi moâi tröôøng Netscape:

Netscape Navigator cung caáp caùc ñoái töôïng cho pheùp JavaScript töông taùc vôùi file HTML, caùc ñoái

töôïng naøy cho pheùp chuùng ta ñieàu khieån vieäc hieån thò thoâng tin vaø ñaùp öùng caùc söï kieän trong moâi

tröôøng Navigator.Ví duï

Ñoái töôïng

Window

Moâ taû

Cung caáp caùc phöông phaùp vaø caùc tính chaát cho cöûa soå hieän haønh

cuûa trình duyeät,bao goàm caùc ñoái töôïng cho moãi frame.

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Location

History

Cung caáp caùc tính chaát vaø phöông phaùp laøm vieäc vôùi caùc ñòa chæ

URL hieän haønh ñöôïc môû.

Caùc ñoái töôïng history cung caáp thoâng tin veà caùc danh saùch cuõ vaø

coù theå giôùi haïn söï töông taùc vôùi danh saùch.

Document

Ñaây laø moät ñoái töôïng ñöôïc söû duïng nhieàu nhaát .Noù chöùa ñöïng caùc

Ñoái töôïng,tính chaát vaø caùc phöông phaùp laøm vieäc vôùi caùc thaønh

phaàn cuûa taøi lieäu nhö caùc :form,link,anchor,applet.

5. Caùc ñoái töôïng do ngöôøi laäp trình xaây döïng:

a. Ñònh nghóa thuoäc tính cuûa ñoái töôïng: (Object Properties)

Cuù phaùp : Object-name.Property-name (teân ñoái töôïng.teân ñaëc tính)

Ví duï :Moät ñoái töôïng airplane coù caùc thuoäc tính nhö sau:

Airplane.model

Airplane.price

Airplane.seating

Airplane.maxspeed

Airplane.fuel

b. Theâm caùc phöông phaùp cho ñoái töôïng:( Method to Object)

Sau khi ñaõ coù caùc thoâng tin veà airplane ta tieáp tuïc xaây döïng phöông phaùp ñeå söû duïng thoâng tin

naøy.Ví duï baïn muoán in ra moâ taû cuûa airplane hoaëc tính toaùn khoaûng caùch toái ña cuûa cuoäc haønh

trình vôùi nhieân lieäu ñaõ coù:

Airplane.description()

Airplane.distance()

c. Taïo moät instance cuûa ñoái töôïng:

Tröôùc khi thao taùc vôùi moät ñoái töôïng cuûa JavaScript ta phaûi taïo moät instance cho ñoái töôïng ñoù.

6 . Nhuùng JavaScript vaøo trong taäp tin HTML:

Cuù phaùp:

JavaScript Program

</SCRIPT>

Thuoäc tính cuûa theû SCRIPT

+ SRC :Ñòa chæ URL chæ ñeán taäp tin chöông trình JavaScript (*.js)

+ LANGUAGE: Chæ ñònh ngoân ngöõ ñöôïc söû duïng trong Script vaø caùc phieân baûn söû duïng (ví duï

nhö :JavaScript ,JavaScript .1.2 vv… ,VBScript).

7. AÅn caùc Scripts ñoái vôùi caùc Browser khoâng cung caáp JavaScript:

<!- - Doøng daáu Script ñoái vôùi caùc Browser khoâng cung caáp (support)

JavaScript Program

//Doøng keát thuùc vieäc daáu Script vaø chuù thích - - >

</SCRIPT>

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8. Söû duïng taäp tin JavaScript beân ngoaøi :

<!- - Doøng daáu Script ñoái vôùi caùc Browser khoâng cung caáp (support)

JavaScript Program

//Doøng keát thuùc vieäc daáu Script vaø chuù thích - - >

</SCRIPT>

9. Theâm chöông trình vaøo taäp tin HTML:

<HTML>

<HEAD>

<TITLE>Listing 2.1</TITLE>

</HEAD>

<BODY>

Here is result:

<!--

document.writeln("It work<BR>");

-->

</SCRIPT>

</BODY>

</HTML>

Baøi 2: SÖÛ DUÏNG JAVASCRIPT

1. Cuù phaùp cô baûn cuûa leänh :

JavaScript xaây döïng caùc haøm,caùc phaùt bieåu,caùc toaùn töû vaø caùc bieåu thöùc treân cuøng moät doøng vaø

keát thuùc baèng ;

Ví duï: document.writeln("It work<BR>");

2. Caùc khoái leänh:

Nhieàu doøng leänh coù theå ñöôïc lieân keát vôùi nhau vaø ñöôïc bao bôûi { }

Ví duï:

{

document.writeln("Does It work");

document.writeln("It work!");

}

3. Xuaát döõ lieäu ra cöûa soå trình duyeät:

Duøng 2 phöông phaùp document.write() vaø document.writeln()

Ví duï:

document.write(“Test”);

document.writeln(“Test”);

4. Xuaát caùc theû HTML töø JavaScript

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Ví duï 1:

<!- -

document.write("This is text bold </B>");

<HTML>

<HEAD>

<TITLE>Outputting Text</TITLE>

- ->

</HEAD>

</SCRIPT>

</BODY>

</HTML>

<BODY>

This is text plain <BR>

<B>

Ví duï 2:

document.write('<IMG

SRC="welcome.gif">');

document.write("<BR><H1>WELCOME TO

NETSCAPE 2.1</H1>");

- ->

<HTML>

<HEAD>

<TITLE>Example 2.4 </TITLE>

</HEAD>

<BODY>

<!- -

</SCRIPT>

</BODY>

</HTML>

5. Söû duïng phöông phaùp writeln() vôùi theû PRE:

<HTML>

document.writeln("Two,");

<HEAD>

document.write("Three");

document.write("...");

<TITLE>Outputting Text</TITLE>

</HEAD>

<BODY>

<PRE>

- ->

</SCRIPT>

</PRE>

<!- -

</BODY>

</HTML>

document.writeln("One,");

6. Caùc kí töï ñaëc bieät trong chuoåi:

\n : New line

\t : Tab

\r : carriage return

\f : form feed

\b: backspace

Ví duï:

document.writeln("It work!\n");

7. Laøm vieäc vôùi caùc dialog boxes

Söû duïng haøm alert() ñeå hieån thò thoâng baùo trong moät hoäp.

Ví duï:

alert("Welcome to Netscape Navigator

<HTML>

21");

<HEAD>

<TITLE>Example 2.5 </TITLE>

</HEAD>

<BODY>

document.write('<IMG

SRC="welcome.gif">');

- ->

<!- -

</SCRIPT>

</BODY>

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8. Töông taùc vôùi ngöôøi söû duïng:

Söû duïng phöông phaùp promt() ñeå töông taùc vôùi ngöôøi söû duïng.

Ví duï 1:

<HTML>

document.write("Your favorite color

<HEAD>

is:");

document.writeln(prompt("enter your

<TITLE>Listing 2.6</TITLE>

favorite color:","Blue"));

</HEAD>

<BODY>

- ->

<!- -

</SCRIPT>

</BODY>

</HTML>

Ví duï 2:

<HTML>

document.write("<H1>Greeting ,");

document.writeln(prompt("enter your

<HEAD>

name:","name"));

document.write("Welcome to netscape

<TITLE>Listing 2.6</TITLE>

</HEAD>

<BODY>

navigator 2.01 </H1>");

- ->

</SCRIPT>

</BODY>

</HTML>

<!- -

document.write('<IMG

SRC="welcome.gif">');

Söû duïng daáu + ñeå coäng 2 chuoåi ñôn laïi:

Ví duï 3:

document.write("<H1>Greeting ," +

<HTML>

prompt("enter your name:","name") + "

<HEAD>

<TITLE>Listing 2.6</TITLE>

</HEAD>

<BODY>

Welcome to netscape navigator 2.01

</H1>");

- ->

<!- -

document.write('<IMG

SRC="welcome.gif">');

</SCRIPT>

</BODY>

</HTML>

9. Caùc kieåu döõ lieäu trong JavaScript:

a. Döõ lieäu kieåu soá:

+ Soá nguyeân: ví duï 720

+ Soá Octal: ví duï :056

+ Soá Hexa:ví duï:0x5F

+ Soá thaäp phaân :ví duï :7.24 , -34.2 ,2E3

b. Döõ lieäu kieåu chuoåi:

ví duï: ” Hello”

’245’

“ “

c. Döõ lieäu kieåu Boolean:

Keát quaû traû veà laø true hoaëc false.

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d. Döõ lieäu kieåu null:

Traû veà giaù trò roãng.

e. Döõ lieäu kieåu vaên baûn (gioáng nhö kieåu chuoåi)

10. Taïo bieán trong JavaScript:

Var example;

Var example=”Hello”;

Ta coù theå duøng document.write(example); ñeå xuaát noäi dung cuûa bieán.

Ví duï 1: duøng töø khoùa var ñeå khai baùo bieán

<HTML>

<HEAD>

<BODY>

<!--

<TITLE>Example 3.1</TITLE>

document.write('<IMG

SRC="Welcome.gif">');

document.write("<H1>Greeting ," +

name + " Welcome to netscape

navigator 2.01 </H1>");

-->

<!- -

var name=prompt("enter your

name:","name");

- ->

</SCRIPT>

</BODY>

</HTML>

</HEAD>

Ví du 2: taïo laïi moät giaù trò môùi cho bieán

<HTML>

</HEAD>

<HEAD>

<BODY>

<TITLE>Example 3.2</TITLE>

<!--

var name=prompt("enter your

name:","name");

alert ("greeting " + name + " , ");

name=prompt("enter your friend's

name:","friend's name");

document.write('<IMG

SRC="Welcome.gif">');

document.write("<H1>Greeting ," +

name + " Welcome to netscape

navigator 2.01 </H1>");

-->

</SCRIPT>

</BODY>

</HTML>

11. Laøm vieäc vôùi bieán vaø bieåu thöùc:

•

Thieát laäp bieåu thöùc:

Cuù phaùp: <bieán> <toaùn töû > <bieåu thöùc>

* Toaùn töû:

= Thieát laäp giaù trò beân phaûi cho beân traùi

Ví duï :x=5

+= Coäng traùi vaø phaûi ,sau ñoù gaùn keát quaû cho beân traùi pheùp toaùn

Ví duï: cho x=10,y=5

x+=y => x=15

-= Tröø beân traùi cho beân phaûi ,gaùn keát quaû laïi cho beân traùi

x-=y => x=5

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*= Nhaân beân traùi cho beân phaûi,gaùn keát quaû cho beân traùi

x*=y => x=50

/= Chia beân traùi cho phaûi ,gaùn keát quaû laïi cho beân traùi

x/=y => x=2

%= Chia beân traùi cho beân phaûi vaø laáy soá dö gaùn laïi cho beân traùi

x%=y => x=0

* Caùc toaùn töû khaùc:

Ví duï:

x+=15+3

y=++x; (=> y=6 vì x taêng leân 6)

=> x=18

8+5

32.5 * 72.3

12 % 5

z=x++; (=> z=6 vì sau ñoù x gaùn cho z)

sau ñoù x taêng 1 => x=7

Do ñoù ta coù keát quaû cuoái cuøng laø:

x=7;y=6;z=6;

Daáu ++ vaø daáu - - vaø daáu -

Ví duï:

x=5;

Ví duï: x=5;

x=-x => x=-5

•

Pheùp toaùn Logic

&& : vaø

||: hoaëc

! not

Ví duï:

x=5 ,y=2 ,c=3

(x>y) && (x>c)

false && anything is always false

(x>y) || (c<x) => true

!x

•

Toaùn töû so saùnh trong JavaScript:

==

!=

1==1 => true

3<1 =>false

>

<

>=

5 >=4 =>true

“the” != “he” => true

4==”4” =>true

<=

Ví duï:

•

Toaùn töû ñieàu kieän:

Cuù phaùp:

(ñieàu kieän ) ? giaù trò 1 : giaù trò 2

Neáu ñieàu kieän ñuùng thì traû veà giaù trò 1

Neáu ñieàu kieän sai thì traû veà giaù trò 2

Ví duï:

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(day=”Saturday”) ? “Weekend” : “Not Saturday”

Toaùn töû chuoåi:

•

“ Welcome to “ + “ Netscape Navigator”

Ví duï:

Var welcome=”Welcome to”

Welcome += “ Netscape Navigator”

ꢀ welcome= “Welcome to Netsacpe Navigator”

Ví duï : Söû duïng toaùn töû ñieàu kieän ñeå kieåm tra ngoû vaøo

var output = (response==answer) ?

correct:incorrect;

</SCRIPT>

<HTML>

<HEAD>

<TITLE>Example 3.3</TITLE>

</HEAD>

var question="What is 10+10 ?";

var answer=20;

<BODY>

var correct='<IMG

<!--

SRC="correct.gif">';

var incorrect='<IMG

document.write(output);

-->

SRC="incorect.gif">';

var response=prompt(question,"0");

</SCRIPT>

</BODY>

</HTML>

12. Caáu truùc ñieàu kieän if – else

if ñieàu kieän

leänh ;

if ñieàu kieän {

Maõ JavaScript

}

Ví duï:

If (day!=”Saturday”) {

if (day==”Saturday”) {

document.writeln(“It‘s the weekend”);

alert(“ It’s the weekend”);

}

Ví duï:

If (day==”Saturday”) {

document.writeln(“It‘s the weekend”);

}

document.writeln(“It‘s not Saturday”);

}

Söû duïng caáu truùc else – if cho ví duï ôû treân

If (day==”Saturday”) {

document.writeln(“It‘s the weekend”);

}

else {

document.writeln(“It‘s not Saturday”);

}

Caáu truùc keát hôïp :

if ñieàu kieän 1 {

Caùc leänh JavaScript

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if ñieàu kieän 2 {

Caùc leänh JavaScript

} else {

caùc leänh khaùc

}

Caùc leänh JavaScript

} else {

Caùc leänh khaùc

}

Ví duï 1 : Söû duïng phöông phaùp confirm() vôùi phaùt bieåu if

<HTML>

response=prompt(question,"0");

<HEAD>

}

<TITLE>Example 3.3</TITLE>

var output = (response ==answer ) ?

correct:incorrect ;

var question="What is 10+10 ?";

var answer=20;

</SCRIPT>

var correct='<IMG

SRC="correct.gif">';

var incorrect='<IMG

SRC="incorect.gif">';

</HEAD>

<BODY>

<!--

var response=prompt(question,"0");

document.write(output);

-->

if (response != answer) {

if (confirm("Wrong ! press OK for

a second change"))

</SCRIPT>

</BODY>

</HTML>

Ví duï 2 : Söû duïng phöông phaùp confirm() vôùi phaùt bieåu if - else

<HTML>

question="What is 10*10";

answer=100;

<HEAD>

<TITLE>Example 3.3</TITLE>

response=prompt(question,"0");

var question="What is 10+10 ?";

var answer=20;

}

var correct='<IMG

SRC="correct.gif">';

var incorrect='<IMG

var output = (response ==answer ) ?

correct:incorrect ;

SRC="incorect.gif">';

</SCRIPT>

var response=prompt(question,"0");

</HEAD>

<BODY>

if (response != answer) {

if (confirm("Wrong ! press OK for

a second change"))

<!--

document.write(output);

response=prompt(question,"0");

-->

}else {

</SCRIPT>

</BODY>

</HTML>

if (confirm("Correct ! press OK

for a second question"))

{

MTWRFSS

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BAØI 3: HAØM VAØ ÑOÁI TÖÔÏNG

Trong kyõ thuaät laäp trình caùc laäp trình vieân thöôøng söû duïng haøm ñeå thöïc hieän moät ñoaïn chöông

trình theå hieän cho moät module naøo ñoù ñeå thöïc hieän moät coâng vieäc naøo ñoù.

Trong Javascript coù caùc haøm ñöôïc xaây döïng saün ñeå giuùp baïn thöïc hieän moät chöùc naêng naøo ñoù ví

duï nhö haøm alert(), document.write(), parseInt() vaø baïn cuõng coù theå ñònh nghóa ra caùc haøm khaùc

cuûa mình ñeå thöïc hieän moät coâng vieäc naøo ñoù cuûa baïn, ñeå ñònh nghóa haøm baïn theo cuù phaùp sau:

function function_name(parameters, arguments)

{

command block

}

Truyeàn tham soá:

function printName(name) {

document.write(“<HR>Your Name is <B><I>”);

document.write(name);

document.write(“</B></I><HR>”);

}

Ví duï:

Goïi haøm printName()vôùi leänh sau printName(“Bob”);

Khi haøm printName()ñöôïc thi haønh giaù trò cuûa name laø "Bob" neáu goïi haøm

printName()vôùi ñoái soá laø moät bieán

var user = “John”;

printName(user);

Khi ñoù name laø “John”. Neáu baïn muoán thay ñoåi giaù trò cuûa name baïn coù theå laøm nhö sau : name

= “Mr. “ + name;

Phaïm vi cuûa bieán:

Bieán toaøn cuïc (Global variable)

Bieán cuïc boä (Local variable)

Traû veà caùc giaù trò:

Ví duï:

Duøng return ñeå traû veà giaù trò cuûa bieán cube.

MTWRFSS

function cube(number) {

var cube = number * number * number;

return cube;

}

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Ví duï:

MTWRFSS

<HTML>

//CHECK THE RESULT

<HEAD>

return (response == answer) ? correct

: incorrect;

}

// STOP HIDING FROM OTHER BROWSERS --

>

</SCRIPT>

</HEAD<

<TITLE>Example 4.1</TITLE>

<!-- HIDE FROM OTHER BROWSERS

//DEFINE FUNCTION testQuestion()

function testQuestion(question) {

//DEFINE LOCAL VARIABLES FOR THE

FUNCTION

<BODY>

var answer=eval(question);

var output=”What is “ + question +

“?”;

var correct=’<IMG

SRC=”correct.gif”>’;

var incorrect=’<IMG

SRC=”incorrect.gif”>’;

//ASK THE QUESTION

<!-- HIDE FROM OTHER BROWSERS

//ASK QUESTION AND OUTPUT RESULTS

var result=testQuestion(“10 + 10”);

document.write(result);

//STOP HIDING FROM OTHER BROWSERS -->

</SCRIPT>

</BODY>

var response=prompt(output,”0");

</HTML>

Haøm eval duøng chuyeån ñoåi giaù trò chuoåi soá thaønh giaù trò soá

eval(“10*10”)traû veà giaù trò laø 100

Haøm goïi laïi haøm:

Ví duï:

<HTML>

//CHECK THE RESULT

<HEAD>

return (response == answer) ? correct

: testQuestion(question);

<TITLE>Example 4.2</TITLE>

<!-- HIDE FROM OTHER BROWSERS

//DEFINE FUNCTION testQuestion()

function testQuestion(question) {

//DEFINE LOCAL VARIABLES FOR THE

FUNCTION

}

// STOP HIDING FROM OTHER BROWSERS --

>

</SCRIPT>

</HEAD<

<BODY>

var answer=eval(question);

var output=”What is “ + question +

“?”;

var correct=’<IMG

SRC=”correct.gif”>’;

var incorrect=’<IMG

<!-- HIDE FROM OTHER BROWSERS

//ASK QUESTION AND OUTPUT RESULTS

var result=testQuestion(“10 + 10”);

document.write(result);

//STOP HIDING FROM OTHER BROWSERS -->

</SCRIPT>

SRC=”incorrect.gif”>’;

//ASK THE QUESTION

var response=prompt(output,”0");

</BODY>

</HTML>

Ví duï 2:

<HTML>

//DEFINE LOCAL VARIABLES FOR THE

FUNCTION

<HEAD>

<TITLE>Example 4.2</TITLE>

<!-- HIDE FROM OTHER BROWSERS

//DEFINE FUNCTION testQuestion()

function

var answer=eval(question);

var output=”What is “ + question +

“?”;

var correct=’<IMG

SRC=”correct.gif”>’;

testQuestion(question,chances) {

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var incorrect=’<IMG

SRC=”incorrect.gif”>’;

// STOP HIDING FROM OTHER BROWSERS --

>

4

</SCRIPT>

//ASK THE QUESTION

</HEAD>

var response=prompt(output,”0");

//CHECK THE RESULT

if (chances > 1) {

return (response == answer) ? correct

: testQuestion(question,chances-1);

} else {

return (response == answer) ? correct

: incorrect;

<BODY>

<!-- HIDE FROM OTHER BROWSERS

//ASK QUESTION AND OUTPUT RESULTS

var result=testQuestion(“10 + 10”,3);

document.write(result);

//STOP HIDING FROM OTHER BROWSERS -->

</SCRIPT>

}

</BODY>

</HTML>

Baøi 4: TAÏO ÑOÁI TÖÔÏNG TRONG JAVASCRIPT

1. Ñònh nghóa thuoäc tính cuûa ñoái töôïng:

function student(name,age, grade) {

this.name = name;

this.age = age;

this.grade = grade;

}

Ñeå taïo moät Object ta söû duïng phaùt bieåu new.Ví duï ñeå taïo ñoái töôïng student1

student1 = new student(“Bob”,10,75);

3 thuoäc tính cuûa ñoái töôïng student1 laø :

student1.name

student1.age

student1.grade

Ví duï ñeå taïo ñoái töôïng student2

student2 = new student(“Jane”,9,82);

Ñeå theâm thuoäc tính cho student1 baïn coù theå laøm nhö sau:

student1.mother = “Susan”; hoaëc baïn coù theå ñònh nghóa laïi haøm student

MTWRFSS

4

function student(name, age, grade, mother) {

this.name = name;

this.age = age;

this.grade = grade;

this.mother = mother;

}

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Ñoái töôïng laø thuoäc tính cuûa ñoái töôïng khaùc

Ví duï:

function grade (math, english, science) {

this.math = math;

this.english = english;

this.science = science;

}

bobGrade = new grade(75,80,77);

janeGrade = new grade(82,88,75);

student1 = new student(“Bob”,10,bobGrade);

student2 = new student(“Jane”,9,janeGrade);

student1.grade.math:duøng ñeå laáy ñieåm Toaùn cuûa student1

student2.grade.science: duøng laáy ñieåm moân Khoa hoïc cuûa student2

2. Theâm phöông phaùp cho ñoái töôïng:

function displayProfile() {

document.write(“Name: “ + this.name + “<BR>”);

document.write(“Age: “ + this.age + “<BR>”);

document.write(“Mother’s Name: “ + this.mother + “<BR>”);

document.write(“Math Grade: “ + this.grade.math + “<BR>”);

document.write(“English Grade: “ + this.grade.english + “<BR>”);

document.write(“Science Grade: “ + this.grade.science + “<BR>”);

}

function student(name,age, grade) {

this.name = name;

this.age = age;

this.grade = grade;

this.mother = mother;

this.displayProfile = displayProfile;

}

student1.displayProfile();

Ví du:

4

<HTML>

function displayInfo() {

<HEAD>

document.write(“<H1>Employee Profile:

“ + this.name + “</H1><HR><PRE>”);

document.writeln(“Employee Number: “

+ this.number);

<TITLE>Example 4.3</TITLE>

<!-- HIDE FROM OTHER BROWSERS

//DEFINE METHOD

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document.writeln(“Social Security

Number: “ + this.socsec);

document.writeln(“Annual Salary: “ +

this.salary);

// STOP HIDING FROM OTHER BROWSERS --

>

</SCRIPT>

</HEAD>

document.write(“</PRE>”);

}

//DEFINE OBJECT

<BODY>

<!-- HIDE FROM OTHER BROWSERS

function employee() {

this.name=prompt(“Enter Employee’s

newEmployee.displayInfo();

// STOP HIDING FROM OTHER BROWSERS --

Name”,”Name”);

>

this.number=prompt(“Enter Employee

Number for “ + this.name,”000-000");

this.socsec=prompt(“Enter Social

Security Number for “ +

this.name,”000-00-0000");

this.salary=prompt(“Enter Annual

Salary for “ + this.name,”$00,000");

this.displayInfo=displayInfo;

}

</SCRIPT>

</BODY>

</HTML>

newEmployee=new employee();

Vi du:

<!-- Begin

myhours = mydate.getHours();

ampmhour = (myhours > 12) ? myhours -

12 : myhours;

var day="";

var month="";

var ampm="";

ampm = (myhours >= 12) ? 'Buoå i Chieà u '

: ' Buoå i Saù ng ';

var ampmhour="";

var myweekday="";

var year="";

mytime = mydate.getMinutes();

myminutes = ((mytime < 10) ? ':0' :

':') + mytime;

mydate = new Date();

myday = mydate.getDay();

mymonth = mydate.getMonth();

myweekday= mydate.getDate();

weekday= myweekday;

myyear= mydate.getYear();

year = myyear;

if(myday == 0)

day = " Chuû Nhaä t , ";

else if(myday == 1)

day = " Thöù hai, ";

else if(myday == 2)

day = " Thöù ba, ";

else if(myday == 3)

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day = " Thöù tö, ";

else if(mymonth ==5)

month = "thaù ng saù u ";

else if(mymonth ==6)

month = "thaù ng baû y ";

else if(mymonth ==7)

month = "thaù ng taù m ";

else if(mymonth ==8)

month = "thaù ng chín ";

else if(mymonth ==9)

month = "thaù ng möôø i ";

else if(mymonth ==10)

month = "thaù ng möôø i moä t ";

else if(mymonth ==11)

month = "thaù ng möôø i hai ";

// End -->

else if(myday == 4)

day = " Thöù naê m, ";

else if(myday == 5)

day = " Thöù saù u , ";

else if(myday == 6)

day = " Thöù baû y , ";

if(mymonth == 0) {

month = "thaù ng moä t ";}

else if(mymonth ==1)

month = "thaù ng hai ";

else if(mymonth ==2)

month = "thaù ng ba ";

else if(mymonth ==3)

month = "thaù ng tö ";

else if(mymonth ==4)

month = "thaù ng naê m, ";

</script>

Trong phaàn body baïn coù theå xuaát ra daïng nhö sau:

<body>

document.write("<b><font color=#0000ff face='VNI-

Times,helvetica,arial'>" + ampmhour + "" + myminutes + ampm)

document.write("

-

" + day + " ngaø y " + myweekday +" ");

document.write( month + " , naê m " + year + "</font>");

</script>

</body>

Baøi 5: SÖÏ KIEÄN TRONG JAVASCRIPT

Caùc söï kieän cung caáp caùc töông taùc vôùi cöûa soå trình duyeät vaø taøi lieäu hieän haønh ñang ñöôïc load

trong trang web, caùc haønh ñoäng cuûa user khi nhaäp döõ lieäu vaøo form vaø khi click vaøo caùc button

trong form.

Khi söû duïng boä quaûn lyù söï kieän baïn coù theå vieát caùc haøm ñeå bieåu dieãn cho caùc haønh ñoäng döïa vaøo

caùc söï kieän ñöïoc choïn

Baûng söï kieän trong Javascript

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Teân söï kieän

blur

Moâ taû

Xaõy ra khi ñieåm taäp trungcuûa ngoõ vaøo ñöôïc di chuyeån ra

khoûi moät thaønh phaàn cuûa Form (Khi user click ra ngoaøi moät

tröôøng)

click

Khi user Click vaøo 1 link hoaëc thaønh phaàn cuûa Form.

change

focus

load

mouseover

select

submit

unload

Xaõy ra khi giaù trò cuûa Form Field bò thay ñoåi bôûi user.

Xaõy ra khi ngoõ vaøo taäp trung vaøo thaønh phaàn cuûa Form

Xaõy ra khi moät trang ñöôïc Load vaøo trong boä duyeät.

Xaõy ra khi User di chuyeån mouse qua moät Hyperlink.

Xaõy ra khi User choïn 1 tröôøng cuûa thaønh phaàn Form.

Xaõy ra khi User xaùc nhaän ñaõ nhaäp xong döõ lieäu.

Xaõy ra khi User rôøi khoûi trang Web.

Boä quaûn lyù söï kieän (Event Handler)

Ñeå quaûn lyù caùc söï kieän trong javascript ta duøng caùc boä quaûn lyù söï kieän.

Cuù phaùp cuûa moät boä quaûn lyù söï kieän:

<HTML_TAG OTHER_ATTRIBUTES eventHandler=”JavaScript Program”>

Ví duï:

Ví duï:

<INPUT TYPE=”text” onChange=”

if (parseInt(this.value) <= 5) {

alert(‘Please enter a number greater than 5.’);

}

“>

Ví duï:

<INPUT TYPE=”text” onChange=”

alert(‘Thanks for the entry.’);

confirm(‘Do you want to continue?’);

“>

Töø khoùa this: quy cho ñoái töôïng hieän haønh.Trong Javascript Form laø moä ñoái töôïng.Caùc thaønh

phaàn cuûa Form bao goàm text fields, checkboxes, radio buttons, buttons, vaø selection lists.

Ví duï:

Caùc boä quaûn lyù söï kieän trong Javascript

Ñoái töôïng

Boä quaûn lyù söï kieän töông öùng.

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PAGE: 16

Selection list

Text element

Textarea element

Button element

Checkbox

Radio button

Hypertext link

Reset button

Submit button

Document

onBlur, onChange, onFocus

onBlur, onChange, onFocus, onSelect

OnClick

onClick

OnClick

onClick, onMouseOver

OnClick

onLoad, onUnload

Window

Form

onLoad, onUnload

onSubmit

5

Caùch duøng boä quaûn lyù söï kieän onLoad & onUnload

<HTML>

<HEAD>

<TITLE>Example 5.1</TITLE>

</HEAD>

<BODY onLoad=”alert(‘Welcome to my page!’);”

onUnload=”alert(‘Goodbye! Sorry to see you go!’);”>

</BODY>

</HTML>

MTWRFSS

Vi du:

<HTML>

<HEAD>

<TITLE>Example 5.1</TITLE>

<!-- HIDE FROM OTHER BROWSERS

var name = “”;

// STOP HIDING FROM OTHER BROWSERS -->

</SCRIPT>

</HEAD>

<BODY onLoad=”

name = prompt(‘Enter Your Name:’,’Name’);

alert(‘Greetings ‘ + name + ‘, welcome to my page!’);”

onUnload=” alert(Goodbye ‘ + name + ‘, sorry to see you go!’);”>

</BODY>

</HTML>

Vi du

MTWRFSS

<HTML>

<HEAD>

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<TITLE>Example 5.1</TITLE>

<!-- HIDE FROM OTHER BROWSERS

// DEFINE GLOBAL VARIABLE

var name = “”;

function hello() {

name = prompt(‘Enter Your Name:’,’Name’);

alert(‘Greetings ‘ + name + ‘, welcome to my page!’);

}

function goodbye() {

alert(Goodbye ‘ + name + ‘, sorry to see you go!’);

}

// STOP HIDING FROM OTHER BROWSERS -->

</SCRIPT>

</HEAD>

</BODY>

</HTML>

Caùc söï kieän vaø Form

Cac söï kieän ñöôïc söû duïng ñeå truy xuaát Form nhö:

OnClick, onSubmit, onFocus, onBlur, vaø onChange.

Ví duï:

<INPUT TYPE=text NAME=”test” VALUE=”test”

onBlur=”alert(‘Thank You!’);”

onChange=”check(this);”>

Khi giaù trò thay ñoåi function check() seõ ñöôïc goïi. Ta duøng töø khoùa this ñeå chuyeån ñoái töôïng cuûa

tröôøng hieän haønh ñeán haøm check()

Baïn cuõng coù theå döïa vaøo caùc phöông phaùp vaø caùc thuoäc tính cuûa ñoái töôïng baèng phaùt bieåu sau:

this.methodName() & this.propertyName.

Ví duï:

<HTML>

<HEAD>

expression”,””);

calculate(form);

<TITLE>Example 5.3</TITLE>

}

//STOP HIDING FROM OTHER BROWSERS -->

<!-- HIDE FROM OTHER BROWSERS

function calculate(form) {

form.results.value =

eval(form.entry.value);

}

</SCRIPT>

</HEAD>

<BODY>

Enter a JavaScript mathematical

expression:

function getExpression(form) {

form.entry.blur();

<INPUT TYPE=text NAME=”entry”

VALUE=””

form.entry.value = prompt(“Please

enter a JavaScript mathematical

onFocus=”getExpression(this.form);”>

<BR>

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The result of this expression is:

<INPUT TYPE=text NAME=”results”

VALUE=””

</FORM>

</BODY>

</HTML>

onFocus=”this.blur();”>

MTWRFSS

formObjectName.fieldname:Duøng ñeå chæ teân tröôøng cuûa hieän haønh trong Form.

formObjectName.fieldname.value:duøng laáy giaù trò cuûa tröôøng form hieän haønh.

Söû duïng voøng laëp trong JavaScript

1 . Voøng laëp for :

Cuù phaùp :

for ( init value ; condition ; update expression )

Ví duï :

for (i = 0 ; i < 5 ; i++)

{

leänh ;

}

Ví duï:

<HTML>

<HEAD>

<TITLE> for loop Examle </TITLE>

</HEAD>

<BODY>

<!- -

var name=prompt("What is your name?" ,"name");

var query= " " ;

document.write("<H1>" + name + " 's 10 favorite foods </H1> ");

for (var i=1 ;i<=10;i++)

{

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document.write(i + " " + prompt('Enter food number ' + i, 'food' ) +

'<BR>');

}

- ->

</SCRIPT>

</BODY>

</HTML>

2 . Voøng laëp while :

Cuù phaùp:

While ( ñieàu kieän)

{

leänh JavaScript ;

}

Ví duï:

var num=1;

while(num<=10)

{

document.writeln(num);

num++;

}

Ví duï:

var answer=” “ ;

var correc=100;

var question=” what is 10*10 ?” ;

while(answer!=correct)

{

answer=prompt(question,”0”);

}

3. Taïo maûng vôùi voøng laëp for:

function createArray(num)

{

this.length=num;

for ( var j=0 ; j<num; j++)

this[j]=0;

}

Haøm seõ taïo moät maûng coù giaù trò index baét ñaàu laø 0 vaø gaùn taát caû caùc giaù trò cuûa maûng veà 0 .

Ñeå söû duïng ñoái töôïng maûng ta coù theå laøm nhö sau:

newArray= new createArray(4)

Seõ taïo ra moät maûng goàm 4 thaønh phaàn newArray[0] … NewArray[3]

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