Javascript notes.pdf

Notes

1. 2} = In: 199514 À Netscape (browser) pho=
¿ata named Brandan Eich develobed a

nm user

ee z
second name =- LiveScnifst

At +hot time Jova 18 ee ae

[ale puabose Live Sont
tly inte ete
I x

apt both ane.

ll different pro; jamming Langua, Ben:

_ Common . Y de

= Mocho =>. liveScript >. Tauascaipt

Tn 1002, +hene is another -Gamous browser +hot

| wias internet Exhlonen_ Lniiennsggt browser)
a. wen copied jovaScaibt Jeatuñts made

En 05 Tscaipt

Ns intranet explonts)

ce di
_|___“Titeanet Exblonen > scale —

2. [EemaInteanational = Ecma inbanational is

| an industay association Founded in laas,

dedicated “to the standardization o-

infosmation and. communication Systems.

TasnSenibt + + Ecma > Bema Stnibts -
(Rules)

Problems Anlved “= We oe Scaibti >

4 OA Jon. diferent browser .

Fist | Script.

Est > lago pedis
ESAS 2004. Uinta.a? mejo dect)

Ese CES 2015) > 2015 Biggest update jun Is)
Es¢ is also known as Nodean JavaScupt

ane ol trchwidad Commgnity knash

as Te.a4 had decided iS ten 2018. nie

release javascript with hem feotuns ley

hes : —@ programmed gl a

3. — i y ee Onagranmen pido

= a object we Jangu
|| Back word ee a 8 ids

Variables stones the data which

| Can be changed on. used when me need.
These año - RO: to declasr a
Variable. _

{ke ion ola pe pc ane in in
a en on en EA 3

* || Var vas name =103
2 tet 1er name = 105 —
DRE pane pia ara

ae == ae

4. Dataty ber in TavaSes ip

There ore tusn types 9) Data
| Paimitive :
Non= primitive

| Paimitive dat 12
Almitive eya Oak.

Number:
| null

oz @ programmer

| oat

Undefined

int x

Hess

Nan- Phlmitive —datatapes aus

Object — "

5. Al coment sting de Élus

MIE the pulse CA: began the stag

Fos Exomble t= 00
let sty = ta;

Ss a Console Log Hype Cestad);

| Convest numbe2 into Stalin
—¡ Add a u Bun) with the number’
| Ena Esomples= : suelo

—— det num= lo;

6. — avaScaikt String.

-|stsing:= String ant used to: store textual

= | Jour de Jike word, sentence. TE
à ee based. indexing

== Let ta =" pro”
ER ee Ut stn = “pro;
Ru ns

E | a
E I muasenibt ssi Method

|| taime) Slice) _
| chan atO tostningt
| tomcat) Substning C)
|| index 00 — 2 Enf liees

| tastTndexo3 0 tolomer Case O)

7. 1

TE En Undefined in Tawscaipt-

PS on..uninikialized variable returns

‘Lit tas tte ©

meta (sta); undefined
| Necreaing = none i aa pacbenty $ on object

returns |

a a__put- of - bounds gite element

Actunns undefined 0

null means ‘no value’ assign + variable.

| typeognull aetuans..‘ object?

Null is treated as False value. 2”)

ps pe

8. ona Small Bin tat

Fe Big Tnt_ ig a Primitive Dotatube

| which ía used For lange numeric Values

Zool dale 958-4:

it doesn't Acbnesent decimal values.
| TH 18 used 40 Acpaesent values opa tos

Fi Rp the end of numeric

_ Vas hum= 9876543 219865252442N5

ll

ETS Pas an argument =
ne ss er

en RTE

Vor bum=- E [as+ 65432198 6525279);

O @pacqsammer gal

9. u Teanany Operator

Tt is also called conditional

4 obenadon

Tt takes +hase olenands

TE makes the Code moho conciso.

@ prigsammen-gi xl
a aint

vañiableName = Conditim ? True: False y

T} the Condition is tue expaession after ?.
will executes. Tp it is false, expression after
> (colon) will executes u

@ rares = gl -
Wettoge = 123
let warning;

Ei agers 13 © “(warning = © You con play”)
a + Ciañhing= “6 You Cannot Play”);

Consale.Loep fanion 2

AS You. can Play : Le

10. E Boolean Data Type

Boolean; bac de end only up values.

Aue and falao.

Fox Exomple=
Nas Read = Bu; tulbeof(Read y,
Non Eot= False; Boolean

Prine tales Asn Come as à aault of

Comb aais ons.
Fox Examble:- ___ @ programmer —

Vos X21 ,b=4 ;

console. Leg (za) Louthut

an eee by )

= (Double men A = Known as +e
8. abstract Compasison obmatns

It Combare variables ignores. datatype.

== Tniple equals oberatos.) <= Known as the
Combarisan ojpenaton .
oro Variables as well_datatype.

11. FA —Tauthy and. Falay Values

Tt iso value thot is considered

“nue when encountered in a Boolean Context

Example :-
typ, $4,079,425 to", K pulse‘,

new Date), =42, 125 3.14, -3.14,

AA —Tnfinity , fer

a programmes qi
L Tr is a value that is considentd
(ils ben encountered in a Boolean context
| Example-== jh =

un

Undefined » nulls FA false, >

0, -0, on (Bigrub)

Vas values = 424 ee

if (values) E

222 Console De. 3 Me

RENTE Buta

—+ u Se =

Console. Log (Jalse);- u

Hut nun à 4

12. Control Elow

Dcartsobeoux Te allows ous progam to
make decisions about what code 18 executed

___! and when ar nl

AAA
EN
ya
N
N

| ER Im
RN
ie an, is it ie pont osdes ]
Jed inte Bt? 7

i Oran ojal.
Control Flow have two ty ber of Statements
— Ay Conditional Statements”

1 ehe Statements

A

13. t= Conditional stotements

| año basically, checks +o sec if a certain
condition 1% eithes true on false: TP the

| condition is true then Aun code Ay if its

false then und code 8.

Hangs 8

V yes Ca

ie Statements > Tfelse, äplelse if

Switch ne

:- To perfesm sobetitive task

with fess code.

14. a — Suite Statement

de exluntes am exp

Combase. ita fault with case values and Dee

| the Statement associated with the matching Cage

ie Susitch Cexpaession) 7

TN te

eu of cases.

breaks ~

| Casevalue 2: - @pnagsammer zur

mec ef Casez __

Er ela

{bods of default 3

o res A +o end

—the Set Switch statement.

- — play dene ahi ee

iA optional

1.4 est

15. Fon. Loop

= fom York executes a black of code
as Song as a sbeciPied Condition is true

psy na @ptrasammen-otnl
| fon initializer s Cond tian 5. ite
T
I stotemencts
Il 3
> | Intializent:- T+ is oh expression Hal initialize
the Loop executed once -
? || conditiom:- Tt iso boolean expression. that
+ determines whether the Jon fools should
execute on Sols.
|
> | THeroton:- Fon statement executes the. iterotor
„after each iterotion.
|
4 =
24 ede a 4
pe o font Wh ie 2; (244 41) E
| — Congole- Lg (D Fa:

16. While ‚Da tihile fobs

tahibes tools t= While loop executes Stotements
Da Nong as he" Conditions On. tue. Tf the

——| Condition become false „the Lonh is terminated.
De 3 while Condition) Y
aes U statements

__|Daswhillenbosb< Tn Do while loop the block
of cade. executed once euen before ganz,

+he Condition.

do Y E
statements
3 while (condition) EN

Goran

17. ss @ paogsamne gin!

18. A JavaScript Funckions

Eindtionz- A function isa black of code that

het task.

DER

—function_funName U) X
= _Jkstotements

Eee is declamd using the function

heat: Function la

= N BE.
Br: % a

function funName OF

Statements

5 nue
funNome 053 Call Function

| example — 2 ee ta

LIRE —_——funckion_mylame Of > Declane Fun-

a Console. se il ODE
| royNeme ()3 > Function call
output: Srily

19. | Easy +o understand

Eunchion Aiyumatss- When we «declare function
ne. res the parameters sé

A nes FT me cal Function

ine Speci the nie) uments .

Poe Exomples —

Function example. Posameten E

Console. Lg (Parameter);
i

let ongument = ‘ang’;

example aa) >

20. [E ecu”,

Papin is ended colle ction o oft items,

eerement | item

Index, > ©

STauaSenipbatnaayi characteristics _

T+ Can. hold values of mixed types.

ize 4 is dynamic.

14 @pnags a

Co) Cpets)
A pg

Let aaa = Ely 253 cot]; > Mixed Type
_pets. push | CO Mon key 2), À programe Size

| Annays ane 72n0-based. indexed. En means
A the. APN of << oy at

l'index Zeso.

tet pets =D Era etn 5

oe 01); > festin element

output = Cat

21. Le = fn) Methods :-

Dep It actuans the. number elements

in_an anna.
let num = C1, 2,°3, u];
Console. La (num. dength); Lu

a2 + Ray PushO) T+ adds elaments +o the

end of he ansay.

4
et num = Ci,2,31;
Console -Jog ( num. push (4);
o un

a Pinay Papo; Te nemaves the last element

—— from an eine and nstusns femaved
Ber clement.

am (et num [15,2,3,4)

Let #emovednum = _hum.popt);

= Console. log (num); 1} £15253)
ee at OR la Chemovednum); II.

22. Dra Sipe = Tt aemoves the fisst element ©

and netusns removed element
— from an et :
tet num = [12:5,uJ5 >
(et nemovednum = _hum.shift();
Console -Lo m); {1 2,3,41
me console. dog Loemouednum)s EN
| @pnogrammer -ginl-.
+ adds: elements to the
Suche beginni: 2) on aaa
let num = 01,252,475
log (num -unshiftCo));
il To,1,2,3,41

Li Array Sant) io TH Aosta the items of anos

let hum = [0,254,175 EM
| Console dog (num-sontt)),;
SES) A COB

_—A Anna nevease O i= Tt netuans the neverse
+ items of an i
0% mil) 25450 |
__Console fog ( num, neverse ());
= | Pres,

23. PEN = fuimitive Vs Ketenence Types.

J Paimittve Types Refenence Types |

= |
| | Tt has a dixed Size | Do not have a tixed

2120. in ay

object stoned in the |

heab.

Stoned in the variable |
Locotion is à Pointe

| Fos Examble:- Null; Eva Example :- Annaus,

Sining, Number ; Bool Objects, Functions ».

undefined ¿Symbol Dates

we cannot add,delete| he can add ‚delete

| dota.

update in primitive | update in reference
dato.

: |

24. Spread Operator

[Spaoadopesatos :- Tt is used 40 expand os

Ispread-an-itesable os an array. Tt is dencted

y 2 APA CRA

Si Sa” tr Lady 68, 60) 7;

Console os CansStn); 11 Céat,£Q’, fc? 1
2 onsale Log (+. OnnSts); 11 ABC

| ef ana = Ci,2,3];

let -anaz = Lu. 0311
Console.) e op paolo

Console feo Casa 2); 11 01,22)

7} ILobbend an item +o the +
+ 5%1,push Cu),
Consnle-bop Larra); 11 Ci2,3,47

Congale „dag Coss2)s 11 [y2,5J

25. sing

used +o assign

distinct variables. Y

a 2 Const items = C Books! , Pen” nil” J;
const: Coty p21 items > destnuctuning

3 21 Console. logica); Il Books >

+ Console, log (y); 11 Pen

if << I Pencil

= @p: psammen ain

= ¿ Const Cor, «47 = items
fin Cansole-Leg 00) Books

_ Console. day Cy). IE ‘Pen’, Pencil’)
Note:- We Should use variable with spread
= bee Syntax an the last variable otherniis

Ce. it thao. exñoh.

= T don't like emos! Do you...
Const Ley Il eos

zz zz

26. jects Intnoduction _

21 They ame ae fem ence type

| objects ane goed. to handle neal woxtd data,
objects Stones © data in key value pais.
21 objects don't have index.
ce a que
object declasotion:= -
O che pero ie à, à
<= home. * Coden’, > value
zu key e tne ‚ion.
an rito Console.Log Gpo person); ll object

>| Access dato...
pe Console Log ( peñson.natne) ; Il toder

Console tog. ( peasoniage); Il zo __

Aisne El det notation

Add key-value pain to objects

= | = pensons id = 5;

—— Console. log ( persoh)};

É u U name: coder”, age: 20, id: s 3

27. Bruta cad Annckennratien

Const pernson= Y

E — nome Coden? 3

“person age: 223
4

fey aid as a_stg by default.
Let? access’ data by PP

——Lonsole. pau D ‘name” 1);
IL output =

PSE] 3

Tn above example there ts o key named aa

“pessen age” el access it 10 dot Notation

| dot Nototion= Console leg pesson. rason age);
pa = Pre ek e#hon Be hot
include = between name.

Baacket Notabion:= Ed lan persons peson agé yD

Tt wonks because it Ÿ

le no.

paper gil SES —

28. nn :
Je a a,

=I + last name + Pe
ne | age: 2 (O prog samme. a
NN y
gee tote ke in. His pay era
= en u A outbut:- firstname
ANTE aceenes S44 S lastname.
a BUS | ir ee.
| Console . tg qosint se) U autbut:
U Tt access 1} progsammes
209 5015 gi
ell cme
a ” ,_peason Cee),

Tt access U 2 output: ise

AA „2 Inatname: al
— à

A Fa

29. 3 This method war introduced
_ lin Est. TE takes an object and artusns

On_anhoy xf the. object properties. (key)

—|| Epa. Examble :—

= a Consale “log Cobject keys ( pesson));
Be lo viele

CS erartname”, € Dastname’, “age”
> 3

Object. values) :- It takes an object and
— | Aetuans an ca e A object Valuer.

Eos FT 2 engine gal. =
= __Consol ES values (pesson);

E en
ce , aint? 6719]
PR a 21

—|lObjectuentales O :- Tt takes an object and
e Aetusns the key- Value pain: es

— nb de te
the eg Cot. center ied person);

ee ORAR

30. = Tt assigns properties

ofan object to individual vaniables.

on age -
= Pacgtammer-ginl--

let name = pesson.name ;

EA ape ao =.

ee

ps dntifita ns © _
+ Y name, age 3 = person 5

—Conadde dog (name); Il ‘Codes! —

pe: El Logs 4

s ny Class= € 2% = ponson

= pa in
consobe.tog class) J) 6
No class Rupee person object ‚Then

1 RE Da ae he class.

31. _ Aso Function *— Another way do white a function

Tt is Tntnoduced in the ESG version of Ts

| THs Syntax la Ahortes +han Aequlas Function
Y

—__|}Example:- —— Function Exbxession
let add = function (a,b)?
ae ——— —feeduan ath;
KA E
Abpve Codo perds arrow function
let Madd = Coy dt
setusn ty 5,
| iC ee nn + à
—| [Function "with, -pokametes’ —___
pee (pa) > 3 statements? 11 Syntax 4.
i pi > { Stotements A Il ss Ered

A ae me quete

tas Opt I aye

Aetuxn

Capa gal

ee

32. A ——
ses

= T+ is a behavior. in which a function
los a Variable can be used before declaration

en.) name); ILundepinedl
Ha var name = SE ey zits,
[tt dont Cause on enzor. Because it looks
{| like in execution phase+-
Ele Nan: name, Gpsspaonmer- gil =
= a orme
Nor name= ‘x; yes
„In cose ef let key: y
—|____Console tag (names 11 Reference Essos
I. Fig Nowe Kaya”
: | Tt cause on efron - Tn Case of (ets Variable
— is 12 hoisted but not initialized.
In case. of eel kedo

— Console Log name); I) Ennor
— Const hame = xu 27;
— Conelusion:- (et and const variables ane hoisted
Rule Cannot be acceased before +heis declaratiin

33. Function can be called be

———fame (); > Function called

Declaration & Junction name O Y

ie Console. Log ( © a 0g xamrnes

Ps i> h
out :=_prapsommes.pislan

TypeEnsos. occuxá in cas of

caer expression ae

E A > Eunetion- Expaeäsion
Var name = function()T

console le fe pan gaacomes
a J

name C); U Tybe Ens on
Vas hame=()=> ?

Console „gg (‘programmer girl’);
Br

“Conclusion: TauaScaibt: doraht hoist the function
expressions and arrow functions.

34. ent ahe -

Haxical Scope:= "It means thot a variable defined
—| Outside a function Can be accessible inside
(another function defined after the variable
declasotion. But the cbbosite is not true.

dao boat re add Or
— Vor x= u, am ig hot accessible
cin au ICT ÉRMRS
ti x is accessible he, y 1s Ne
function minus O) x
Nas = 65 > ia accessible

| nf A

= Bk @pregrammertaini -

1 a Ge a

| niotes= he variable. defined. inside. a qunction_—#®
will not be accessible outside the function

In above : code. ia not accesaible

ea tiers tt er the function. __

35. Block Scobe vs Function Scabe

Block Scobe

Eünchian"Seope.

Tt means that the
Variable is accessible

| within +he block I }.

1 I+ means thot the
| Vamables ane onl,
accessible in the ~

pue

let and Const aro.

function in which
thes ono declared

Nos. is a Function

block Scope- Seche.
| Fon Example Fon Eyample~
fon Cletizo3 (co; i428 | Function fun O Y
11 Block von = 425
& 1 i
Console! itu TT de
| we ane trying to Consele-lo
„access let “variable We. Cannot access var
L outside the Scope. outside the function Scobe] |

36. Default Pamea- Tt allows us to give default
= pa A Pañametens if no values

Default parametas

a He
ECN artuxn =
| gs

Console. Dog (add t3,u)); 117

a console. Ag Cadet 53); ILX2S,4=22 4
ps - RETA (add (3); Jet, 42293

no: à parameter has A value is undefined

Er Exomble:- holies
“function add oot 1107

"AR Console. La ae
| ee _

Y rl = imi
ail Organ ag

37. |

Westiftnaemetenas u ia used to gathes parametens

and put them oll_in an asno.

Let's understand with an exomple:=

— function test
Eh — console. Log Ca; lie > outbut
= ° Console dog CH); ia > output
— E 4
DU el tus CS; a);

- testa, 4,4, 6,55
What vill habben with 4, 6,57 2 oobs Nothing
To Cover 3,65 (Rest parametzsa Concept Canes)

Sind ale pus Rest parameter

function test (a, i na,
Aa 11. conaslestan la);
= Console Leg Bd: _

2 RENE

+ dests,a,4,6,5);

{output = 8

38. 8 Couple. of Spec fie

past BR pass os on.-parameter to the

oo. ‚not in_entins object.

—— > Const uses =Y
43 “name? : ‘Alex’,

Ss ur +: {sx QE ali 70? Parom.
— APP 2 det
A O usendetaids ( Lhame, gaed)
Bu nei x
aber Console bo,
raole . La Ca
| CS DS
| = rn —
| —_userdetaits( 9; a
LEA Ed tandis si
| E Alex Re
= Ant sr

39. L “CallBack Function

Lcallbock function:= Tt is defined as, we can alsn

Boss a function as an exce too function.

Y pinction Second (name?
Console og (name);
__Piunetion_finkt ( callback) E

callback ( nlex’);
3

lin... Hast (Second); || output: Alex

| Second Function that is passed as an argument
inside inst function is called à callbèck

Junction. _

= (notes The callback function is helpgul then
you. have to wait. for a seault thot

takes time. =

40. 3 — Jens -
| <toneso DION of unique values _
No_index-hased access

| A antd——
_ [sets one itenable — de
seta have its mon methods.

let items = new set);

a rT
ee Se oe i

Any un eta 2

ad

Object

Can—hawe. dect values nenn Beta

Cannot. pela
«Th Bil la “padined by tnd Whereas
—tilssets tOhnnot oo ais à. 1

41. Const itema= new Set (5

add ©} :- Apbend a. new element to the end
of the set
Fos Exambleï= items. add (“mi”);

| I outhut = Set (1) Y ui}

.

iclens ©): Remove. all the elements and hetusns
ined.
os Examble:- Const items = new Set (Ci, 2,21);

items. clear 0);
output Set Lo) £3

delete CYi- Tt delete a Specific element Aaom
+ ER mi =

Fos. Examble:- Conat items = new Set (11,298,413

itemaidelete (3);
output Setrst 112,47

[host check Whether an element exists in
Sets op not. __ tes
items. hoa (2); lloutputi- tue.

42. ss maps A Mab is -a collection okey =Valuz paisa,

Similar to on object.

Const penton = new Mahl);

Las ot med. mob 2 ie base object

À Map ig Similas to ob in_objects ase

ao Te Sumbels But we Can Es

> aa Key Tn ll

nahe

Const paso = nun. 35 1

_|_peason-set (Name?) Alex);

Zar oe) RA A as

D | hotte € nome” > “alex? 2 aman
I

E 2. > i Sem =

43. |

pete = Retuaned the value associated with
Ed the key

lléstO):— Set the value of the key and returns

| — the mah.

à (deletst:= Delete the entay which has the:key

Same as passed. Kor

1

ai. - Delete all value pairs from
= the mab. $e a

hasc)“- Retusns true if the mab has the.
key provided.

Et ae the new iterator that
Containes the Keys insertion pader

a

44. SS Const pesann= 3

(dicas .
Method _& about : function O€

Name: “6 alex”,
age. 621,

Console. (og (“My name is
$i this-namet”);
2 me 2

_ ME = re — >

| outbut 2 EL nameis alex

then declaiog_a new object „use the object
Litenal , not “the new object C) Constructor.

@pacgaammr-ginden —

45. ra “this” Key wocad sogens o an
object thot 18 executr ¿

9 He cuasent

= piece ef code.

Fon Example
2 ——fünetion Info) E
I NR Be 18 $2 this.

== homer);

MT i

Const pessom = T ERP +
ee __ name: “codes”, ons
Be dao Ti ne

Be ia rn a =

— Const person 22?
—hame =

about: Info.
Fe: at

=> pessont.abaut(); > pessoni name.
== personz, about); > personz home.
— Il outbut:- my name is codes

FRE i myname. is ail.

46. calli: T+ inuokes 4he function and alfous you

A one. by one.

= jokes the Function and alas

!4o pass in arguments as on De

+ land T4 nets a new functions allowing

| +o bass ino this amar and on nd.

Const uses
name: 6Alex?;

Eads! 4 ai 214 Bpnegsammer. se
E PA ¿Junction A

ansehe ug HUES I. ORSAY
a a re A
e Y
Const opio
names ‘Thon’, Iloutput:-

Els athe ae 33 a Thon, 31
Userd. intno- call Cuser 2);

47. Var user? = F hom

= aoe 3
Si function Jay m
Console - It 4 +his name);
HE r

80, -abh (use 2, LH

— li Sutbut = Hi then

beta Example: cae

Var usirt = Tname : CAlex?,
age .21 34 Z BE
var ugen 2 = name: © Thon’,

function li Js.
EY —Consoba big | s. hame , this.aged)
ER y

van smpfun = Any. bind (user 1) ;

ae AS ar

may fun 2);
sal ae SA live

ae a pa =

48. 5 Tt is used +o add new properties
= | ond methods to an Fe Object Constructor
Oe See si à @progdammes aint.

Junction Person OT _—
2! this, name= ‘Tobin’? «
His. ae = 23

A pensoh à Os
de Console . ls (Person. en

value

oil checking the phosaly

a |_paopenties ods {nom a prototype

| bsin a fasten object

2 en since “propentizs | methods on
the prototype dort have 40 be po-cacated
| each time “a new object is created.

49. Re teen des

Arie things o Ho _semember about nen keyword

are contes ._hew object, The ae
| object is sx u

2, || TE sitet +his hem objects internal.

| Tt makes +he this naïabte ere to Fr.

cavated object =)
a ca bj

MITE executes the Constructor function using
|| the newhy cwoted object whenever this —
ar

8 mentioned.

ee

STE petusna He newly capoted object.

50. a=

Bae en Herp tearing |
Keob coding |

How de yu geal lan A

en = ones nn

NE pregeamneqil-