Misconceptions

Here are a couple of misconceptions. Many more to come...

The is no connection between the number of misconceptions listed here and the difficulty of the corresponding programming language. The effort we spent on collecting misconceptions is very different for different languages. It would be inappropriate to reason about the quality of languages based on the number of misconceptions in this collection.

AccessingInexistentPropertyError

Accessing a non existent property on an object produces an error

ArrowFunctionNoImpliedReturn

Even when an arrow function consists just of an expression, the return keyword must be explicitly written

ArrowFunctionRequiresFunctionKeyword

Arrow functions also require the keyword 'function'

CallbackParametersInCaller

Parameters of a callback function may be written as parameters of the caller function

CharType

A single character is of type char

ConditionalOperatorNotExpression

The conditional operator is not an expression

ConstDeclarationCanBeLeftUninitialized

Declarations of constants do not need to be immediately initialized

EqualityOperatorComparesObjectsValues

The equality operator compares two objects' values

EqualityOperatorComparesOnlyTypes

The equality operator '==' compares only the types of the operands

FunctionAsValueWithParentheses

To use a function as a value, one needs to have parentheses after its name

FunctionOverloading

It is possible to create multiple functions with the same name but with different signatures

FunctionsCannotBeImmediatelyInvoked

Functions cannot be called in the expression in which they are defined

FunctionsMustBeNamed

Every function definition requires an associated name

IdentifierAsStringInBracketNotation

An identifier used to access a property with the bracket notation is treated as a string

MandatoryAssignment

An expression must be assigned to have a valid statement

MapInPlace

Map modifies the elements of the array on which it operates in place

NoBracketNotationForObjects

Square brackets cannot be used to access properties of an object

NoFunctionCallsChaining

It is not allowed to chain function calls

NoGlobalObject

There isn't a global object

NoReturnValue

Functions without return statements return no value at all

NullAndUndefinedAreTheSame

The values null and undefined are the same

NumberOfParametersMatchArguments

Functions must be called with the same number of arguments as defined in their signature

ObjectAsParameterIsCopied

Objects are passed by value

PrototypesAreClasses

JavaScript is based on a class-based object model

SetTimeout0IsSynchronous

Scheduling the execution of a function after 0 milliseconds with setTimeout is equivalent to a synchronous call

SetTimeoutReturnsCallbackResult

SetTimeout returns the value returned by the callback function

StringRepetitionOperator

One can repeat a String by multiplying it with a number

TypeofArrayIsArray

The typeof operator applied on an array returns 'array'

TypeofNullIsNull

The value null is of type 'null'

Programming Language

Notional Machine

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