lecture 5 java script.pptx

8/17/2019 Lecture 5 Java Script.pptx

1/73

Introduction to Java Script

JavaScript: Control & Looping Statements


2/73

Control Structures

Sequential execution Statements execute in the order they are written

Transfer of control ext statement to execute may not !e the next one in sequence

Three control structures Sequence structure Selection structure

if if"else switch

#epetition structure while do"while for for"in


3/73

Control Structures

$lowchart %raphical representation of algorithm or portion of algorithm $lowlines

Indicate the order the actions of the algorithm execute

#ectangle sym!ol Indicate any type of action

val sym!ol ' complete algorithm

Small circle sym!ol ' portion of algorithm

(iamond sym!ol Indicates a decision is to !e made


4/73

Control Structures

add grade to total total = total + grade;

add 1 to counter counter = counter + 1;

Flowcharting JavaScript’s sequence structure.


5/73

JavaScript )eywords

JavaScriptKeywords

break case catch continue default delete do else finally for function if in instanceof new return switch this throw try typeof var void while with

Keywords thatare reserved but

not currently

used by JavaScript

abstract boolean byte char class const debugger double enum export

extends final float goto implements import int interface long native package private protected public short static super synchronized throws transient volatile

Fig. 8.2 JavaScript keywords.


6/73

if Selection Statement

Single*entry+single*exit structure

Indicate action only when the condition evaluates totrue


7/73

if Selection Statement

grade > !"true

#alse

print $%assed&

Flowcharting the single'selectionif

state(ent.


8/73

if…else Selection Statement

Indicate different actions to !e perform whencondition is true or false

Conditional operator ,?-

JavaScript.s only ternary operator Three operands

$orms a conditional expression


9/73

if…else Selection Statement

grade > !" true

print $Failed&

#alse

print $%assed&

Flowcharting the dou)le'selection if*else state(ent.


10/73

while #epetition Statement

#epetition structure ,loop- #epeat action while some condition remains true


11/73

while #epetition Statement

product + 1!!!product

" #

producttrue

#alse

Flowcharting the while repetition state(ent.


12/73

$ormulating 'lgorithms:Case Study / ,Counter*Controlled #epetition-

Counter*controlled repetition Counter

Control the num!er of times a set of statements executes

(efinite repetition


13/73

average0html,/ of 1-


14/73

average0html,2 of 1-

24 // Processing Phase

25 while ( gradeCounter


15/73

48

49


16/73

$ormulating 'lgorithms with Top*(own3 Stepwise#efinement: Case Study 2 ,4ser*Controlled #epetition-

Indefinite repetition Sentinel ,4ser Controlled- value


17/73

average20html,/ of 1-


18/73


25 // Processing phase

26 // prompt for input and read grade from user

27 grade = window.prompt(

28 "nter &nteger rade -1 to 2uit!" "0" )#

29

30 // con$ert grade from a string to an integer31 grade%alue = parse&nt( grade )#

32

33 while ( grade%alue 3= -1 ) {

34 // add grade%alue to total

35 total = total ' grade%alue#

36

37 // add 1 to gradeCounter

38 gradeCounter = gradeCounter ' 1#

39

40 // prompt for input and read grade from user

41 grade = window.prompt(

42 "nter &nteger rade -1 to 2uit!" "0" )#

43

44 // con$ert grade from a string to an integer

45 grade%alue = parse&nt( grade )#

46

47


19/73


48 // ermination phase

49 if ( gradeCounter 3= 0 ) {

50 a$erage = total / gradeCounter#

51

52 // displa* a$erage of e+am grades

53 document.writeln(

54 "


20/73


21/73

$ormulating 'lgorithms with Top*(own3 Stepwise#efinement: Case Study 1 ,ested Control Structures-

Consider pro!lem

5a6e o!servations

Top*down3 stepwise refinement


22/73

analysis0html,/ of 2-

1


23/73

analysis0html,2 of 2-

25 if ( result == "1" )

26 passes = passes ' 1#

27 else

28 failures = failures ' 1#

29

30 student = student ' 1#31

32

33 // termination phase

34 document.writeln( "


24/73


25/73


26/73

'ssignment perators

Compound assignment operators '!!reviate assignment expressions


27/73

'ssignment perators


28/73

Increment and (ecrement perators

7reincrement or predecrement operator Increment of decrement operator placed !efore a varia!le

7ostincrement or postdecrement operator Increment of decrement operator placed after a varia!le


29/73


1


30/73

increment0html,/ of 2-

1


31/73

26 // increment then print K

27 document.writeln( "


32/73



33/73

8ssentials of Counter*Controlled #epetition

Counter*controlled repetition ame of a control Initial value Increment or decrement $inal value


34/73

9hileCounter0html,/ of 2-

1


35/73

9hileCounter0html,2 of 2-

25


36/73

for #epetition Statement

for repetition statement andles all the details of counter*controlled repetition


37/73

$orCounter0html,/ of /-

1


38/73


39/73


for $ var counter = 1; counter %=&; ++counter '

Initial value o# control varia)le Increment o# control varia)le

,ontrol varia)le name Final value o# control varia)le

#or which the condition is true

for keyword

-oop'continuation condition


40/73


counter %= &

document(writeln$

)%p style=*)fontsize ) + counter +

)ex*),-./0 font size ) +

counter + )ex%2p,) ';

true

#alse

var counter = 1

++counter

sta)lish

initial valueo# control

varia)le.

/eter(ine

i# final value

o# control

varia)lehas )een

reached.

0ody o# loop

this (ay )e (any

state(ents

Increment

the control

varia)le.

Fig. 3.4 for repetition structure #lowchart.


41/73

8xamples 4sing the for Statement

Summation with for

Compound interest calculation with for loop 0ath o!;ect

5ethod pow

5ethod round

1


42/73

Sum0html,/ of /-

1


43/73


44/73

Interest0html,/ of 2-

1


45/73

Interest0html,2 of 2-

26 for ( $ar *ear = 1# *ear


46/73

switch 5ultiple*Selection Statement

Controlling expressionCase la!els

(efault case


47/73

SwitchTest0html,/ of 1-

1


48/73

SwitchTest0html

,2 of 1-

( ) {

24 case "1"!

25 startag = "


49/73

SwitchTest0html

,1 of 1-

49 document.writeln( endag )#

50

51 else

52 document.writeln( "&n$alid choice! " ' choice )#

53 // --,

54


50/73


51/73


52/73

switch 5ultiple*Selection Statement

case a case a actionstrue

#alse

.

.

.

break

case ) actions break

#alse

#alse

case 5 case 5 actions break

default actions

true

true

case )


53/73

do"while #epetition Statement

Similar to the while statementTests the loop continuation condition after the loop

!ody executes

Loop !ody always executes at least once

1 5 l i "1 0"5


54/73

(o9hileTest0html

,/ of 2-

1


55/73

26


56/73

do…while #epetition Structure

conditiontrue

actions

#alse


57/73

break and continue Statements

break Immediate exit from the structure 4sed to escape early from a loop S6ip the remainder of a switch statement

continue S6ips the remaining statements in the !ody of the structure 7roceeds with the next iteration of the loop

1


58/73


59/73

24 ":roe out of loop at count = " ' count )#

25 // --,

26


60/73

ContinueTest0html

,/ of 2-

5+ml $ersion 1.0 5

2


61/73

24 document.writeln( "9sed continue to sip printing J" )#

25 // --,

26


62/73

La!eled break and continue Statements

La!eled break statement


63/73


64/73


65/73


66/73

i l


67/73

Logical perators

5ore logical operators Logical '( , 33 - Logical # , 44 - Logical T , 5 -

i l


68/73

Logical perators

L i l


69/73

Logical perators

1


70/73

Logicalperators0html

,/ of 2-

2


71/73

Logicalperators0html

,2 of 2-

27 "


72/73

L i l t


73/73

Logical perators

lecture 5 java script.pptx

Documents