JavaScript reference
אובייקטים גלובאלים
פרק זה הוא תיעוד של כלל האובייקטים שמובנים כסטנדרט בג'אווה סקריפט, יחד עם המתודות (methods) והתכונות (properties) שלהם.
Value properties
These global properties return a simple value. They have no properties or methods.
Function properties
These global functions—functions which are called globally, rather than on an object—directly return their results to the caller.
Fundamental objects
These are the fundamental, basic objects upon which all other objects are based. This includes general objects, booleans, functions, and symbols.
Error objects
Error objects are a special type of fundamental object. They include the basic Error
type, as well as several specialized error types.
Numbers and dates
These are the base objects representing numbers, dates, and mathematical calculations.
Text processing
These objects represent strings and support manipulating them.
Indexed collections
These objects represent collections of data which are ordered by an index value. This includes (typed) arrays and array-like constructs.
Keyed collections
These objects represent collections which use keys. The iterable collections (Map
and Set
) contain elements which are easily iterated in the order of insertion.
Structured data
These objects represent and interact with structured data buffers and data coded using JavaScript Object Notation (JSON).
Control abstraction objects
Control abstractions can help to structure code, especially async code (without using deeply nested callbacks, for example).
Reflection
Internationalization
Additions to the ECMAScript core for language-sensitive functionalities.
WebAssembly
Other
הצהרות
פרק זה הוא תיעוד של כלל ההצהרות והמשפטים* בג'אווה סקריפט.
* התרגום של statement ו declaration לעברית הוא "הצהרה".
כאן הכוונה להצהרה ( declaration ), לדוגמא - var a = 123.
ומשפט (statement), לדוגמא - משפטי if.
ביטויים ואופרטורים
פרק זה הוא תיעוד של כלל הביטויים והאופרטורים בג'אווה סקריפט.
For an alphabetical listing see the sidebar on the left.
Primary expressions
Basic keywords and general expressions in JavaScript.
this
- The
this
keyword refers to a special property of an execution context. function
- The
function
keyword defines a function expression. class
- The
class
keyword defines a class expression. function*
- The
function*
keyword defines a generator function expression. yield
- Pause and resume a generator function.
yield*
- Delegate to another generator function or iterable object.
async function
- The
async function
defines an async function expression. await
- Pause and resume an async function and wait for the promise's resolution/rejection.
[]
- Array initializer/literal syntax.
{}
- Object initializer/literal syntax.
/ab+c/i
- Regular expression literal syntax.
( )
- Grouping operator.
Left-hand-side expressions
Left values are the destination of an assignment.
- Property accessors
- Member operators provide access to a property or method of an object
(object.property
andobject["property"]
). new
- The
new
operator creates an instance of a constructor. new.target
- In constructors,
new.target
refers to the constructor that was invoked bynew
. import.meta
- An object exposing context-specific metadata to a JavaScript module.
super
- The
super
keyword calls the parent constructor. ...obj
- Spread syntax allows an expression to be expanded in places where multiple arguments (for function calls) or multiple elements (for array literals) are expected.
Increment and decrement
Postfix/prefix increment and postfix/prefix decrement operators.
A++
- Postfix increment operator.
A--
- Postfix decrement operator.
++A
- Prefix increment operator.
--A
- Prefix decrement operator.
Unary operators
A unary operation is an operation with only one operand.
delete
- The
delete
operator deletes a property from an object. void
- The
void
operator discards an expression's return value. typeof
- The
typeof
operator determines the type of a given object. +
- The unary plus operator converts its operand to Number type.
-
- The unary negation operator converts its operand to Number type and then negates it.
~
- Bitwise NOT operator.
!
- Logical NOT operator.
Arithmetic operators
Arithmetic operators take numerical values (either literals or variables) as their operands and return a single numerical value.
+
- Addition operator.
-
- Subtraction operator.
/
- Division operator.
*
- Multiplication operator.
%
- Remainder operator.
**
- Exponentiation operator.
Relational operators
A comparison operator compares its operands and returns a Boolean
value based on whether the comparison is true.
in
- The
in
operator determines whether an object has a given property. instanceof
- The
instanceof
operator determines whether an object is an instance of another object. <
- Less than operator.
>
- Greater than operator.
<=
- Less than or equal operator.
>=
- Greater than or equal operator.
Note: => is not an operator, but the notation for Arrow functions.
Equality operators
The result of evaluating an equality operator is always of type Boolean
based on whether the comparison is true.
Bitwise shift operators
Operations to shift all bits of the operand.
<<
- Bitwise left shift operator.
>>
- Bitwise right shift operator.
>>>
- Bitwise unsigned right shift operator.
Binary bitwise operators
Bitwise operators treat their operands as a set of 32 bits (zeros and ones) and return standard JavaScript numerical values.
Binary logical operators
Logical operators are typically used with boolean (logical) values, and when they are, they return a boolean value.
Conditional (ternary) operator
(condition ? ifTrue : ifFalse)
-
The conditional operator returns one of two values based on the logical value of the condition.
Optional Chaining operator
?.
-
The optional chaining operator returns
undefined
instead of causing an error if a reference is nullish (null
orundefined
).
Assignment operators
An assignment operator assigns a value to its left operand based on the value of its right operand.
=
- Assignment operator.
*=
- Multiplication assignment.
**=
- Exponentiation assignment.
/=
- Division assignment.
%=
- Remainder assignment.
+=
- Addition assignment.
-=
- Subtraction assignment
<<=
- Left shift assignment.
>>=
- Right shift assignment.
>>>=
- Unsigned right shift assignment.
&=
- Bitwise AND assignment.
^=
- Bitwise XOR assignment.
|=
- Bitwise OR assignment.
&&=
- Logical AND assignment.
||=
- Logical OR assignment.
??=
- Logical nullish assignment.
[a, b] = [1, 2]
{a, b} = {a:1, b:2}
-
Destructuring assignment allows you to assign the properties of an array or object to variables using syntax that looks similar to array or object literals.
Comma operator
,
- The comma operator allows multiple expressions to be evaluated in a single statement and returns the result of the last expression.
פונקציות
פרק זה הוא תיעוד של מהלך העבודה עם פונקציות בג'אווה סקריפט בפיתוח תוכנות.
* סביר שיש תרגום טוב יותר למונח rest parameters./