Call by value and call by reference in javascript mdn

Pass The Value

So I have been writing about JavaScript for some time now, I also help a few of my friends learn JavaScript as they want to get into front end development. This is one of the personal favorite topics, but I was a bit surprised to find how many times, people get it wrong.

The problem with JS is that it doesn’t follow the general pattern like other languages. For e.g. in C#, the ref…

This part of the JavaScript section on MDN serves as a repository of facts about the JavaScript language. Read more about this reference.

Built-ins

JavaScript standard built-in objects, along with their methods and properties.

Value properties

globalThis
Infinity
NaN
undefined

Function properties

eval()
isFinite()
isNaN()
parseFloat()
parseInt()
decodeURI()
decodeURIComponent()
encodeURI()
encodeURIComponent()

Fundamental objects

Object
Function
Boolean
Symbol

Error objects

Error
EvalError
RangeError
ReferenceError
SyntaxError
TypeError
URIError
AggregateError

Numbers & dates

Number
BigInt
Math
Date

Text processing

String
RegExp

Indexed Collections

Array
Int8Array
Uint8Array
Uint8ClampedArray
Int16Array
Uint16Array
Int32Array
Uint32Array
BigInt64Array
BigUint64Array
Float32Array
Float64Array

Keyed collections

Map
Set
WeakMap
WeakSet

Structured data

ArrayBuffer
SharedArrayBuffer
DataView
Atomics
JSON

Memory management

WeakRef
FinalizationRegistry

Control abstraction

Promise
GeneratorFunction
AsyncGeneratorFunction
Generator
AsyncGenerator
AsyncFunction

Reflection

Reflect
Proxy

Internationalization

Intl
Intl.Collator
Intl.DateTimeFormat
Intl.DisplayNames
Intl.ListFormat
Intl.Locale
Intl.NumberFormat
Intl.PluralRules
Intl.RelativeTimeFormat
Intl.Segmenter

Statements

JavaScript statements and declarations

Control flow

Block
Empty statement
break
continue
if...else
switch
throw
try...catch

Declarations

var
let
const

Functions and classes

function
function*
async function
async function*
return
class

Iterations

do...while
for
for...in
for...of
for await...of
while

Other

debugger
export
import
label
with

Expressions and operators

JavaScript expressions and operators.

Primary expressions

this
function
class
function*
yield
yield*
async function
async function*
await
[]
{}
/ab+c/i
( )
null

Left-hand-side expressions

Property accessors
?. (Optional chaining)
new
new.target
import.meta
super
...obj

Increment & decrement

A++
A--
++A
--A

Unary operators

delete
void
typeof
+
-
~
!

Arithmetic operators

+
-
/
*
%
**

Relational operators

in
instanceof
<
>
<=
>=

Equality operators

==
!=
===
!==

Bitwise shift operators

<<
>>
>>>

Binary bitwise operators

Binary logical operators

&&
||
??

Conditional (ternary) operator

(condition ? ifTrue : ifFalse)

Assignment operators

=
*=
**=
/=
%=
+=
-=
<<=
>>=
>>>=
&=
^=
|=
&&=
||=
??=
[a, b] = arr
{ a, b } = obj

Comma operators

Functions

JavaScript functions.

Arrow Functions
Default parameters
Rest parameters
arguments
Method definitions
getter
setter

Classes

JavaScript classes.

Additional reference pages

Lexical grammar
Data types and data structures
Strict mode
Deprecated features

What is call by value and call by reference?

Call By Value. Call By Reference. While calling a function, we pass values of variables to it. Such functions are known as “Call By Values”. While calling a function, instead of passing the values of variables, we pass address of variables(location of variables) to the function known as “Call By References.

Is JavaScript by reference or by value?

Therefore, even changing the argument inside the function doesn't affect the variable passed from outside the function. It is important to note that in javascript, all function arguments are always passed by value. That is, JavaScript copies the values of the passing variables into arguments inside of the function.

What is difference between pass by value and pass by reference in JavaScript?

In pass by value in JavaScript, a copy of the original variable is created so any changes made to the copied variable do not affect the original variable. In pass by reference in JavaScript, we pass the reference of the actual parameter. No copy is created in the memory.

What is call by reference with example?

The call by reference method of passing arguments to a function copies the address of an argument into the formal parameter. Inside the function, the address is used to access the actual argument used in the call. It means the changes made to the parameter affect the passed argument.