Appendix E
JavaScript Operators, Syntactical Elements,
and Keywords

=

Assigns the value of the variable on the right to the variable on the left (x=y)

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+=

Adds the two variables and assigns the result to the variable on the left (x+=y is equivalent to x=x+y)

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-=

Subtracts the variable on the right from the variable on the left and assigns the result to the variable on the left (x-=y is equivalent to x=x-y)

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*=

Multiplies the two variables together and assigns the result to the variable on the left (x*=y is equivalent to x=x*y)

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/=

Divides the variable on the left by the variable on the right and assigns the result to the variable on the left (x/=y is equivalent to x=x/y)

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&=

Combines two expressions into a single expression (x&=y is equivalent to x=x&y)

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%=

Divides the variable on the left by the variable on the right and assigns the remainder to the variable on the left (x%=y is equivalent to x=x%y)

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Arithmetic

Operators used for arithmetic functions

+

Adds two variables together (x+y)

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-

Subtracts the variable on the right from the variable on the left (x-y)

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*

Multiplies two variables together (x*y)

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/

Divides the variable the left by the variable on the right (x/y)

%

Calculates the remainder after dividing the variable on the left by the variable on the right (x%y)

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++

Increases the value of a variable by 1 (x++ is equivalent to x=x+1)

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&

Combines two expressions (x & y)

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--

Decreases the value of variable by 1 (x-- is equivalent to x=x-1)

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-

Changes the sign of a variable (-x)

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Comparison

Operators used for comparing expressions

==

Returns true when the two expressions are equal (x==y)

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!=

Returns true when the two expressions are not equal (x!=y)

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!==

Returns true when the values of the two expressions are equal (x!==y)

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>

Returns true when the expression on the left is greater than the expression on the right (x > y)

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<

Returns true when the expression on the left is less than the expression on the right (x < y)

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>=

Returns true when the expression on the left is greater than or equal to the expression on the right (x >= y)

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<=

Returns true when the expression on the left is less than or equal to the expression on the right (x <= y)

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Conditional

Operators used to determine values based on conditions that are either true or false

If condition is true, then this expression equals value1, otherwise it equals value2

Keywords

JavaScript keywords are reserved by JavaScript

infinity

Represents positive infinity (often used with comparison operators)

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this

Refers to the current object

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var

Declares a variable

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with

Allows the declaration of all the properties for an object without directly referencing the object each time

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Logical

Operators used for evaluating true and false expressions

!

Reverses the Boolean value of the expression

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&&

Returns true only if both expressions are true (also known as an AND operator)

||

Returns true when either expression is true (also known as an OR operator)

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|

Returns true if the expression is false, and false if the expression is true (also known as a NEGATION operator)

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Syntax

Syntactical elements

;

Indicates the end of a command line

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/* comments*/

Used for inserting comments within a JavaScript command line

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// comments

Used to create a line of comments

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