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JavaScript Comparison and Logical Operators
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Comparison and Logical operators are used to test for true or false.
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Comparison Operators
Comparison operators are used in logical statements to determine equality or difference between variables or values.
Given that x=5, the table below explains the comparison operators:
Operator Description Example
== is equal to x==8 is false
=== is exactly equal to (value and type) x===5 is true
x==="5" is false
!= is not equal x!=8 is true
> is greater than x>8 is false
< is less than x<8 is true
>= is greater than or equal to x>=8 is false
<= is less than or equal to x<=8 is true
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How Can it be Used
Comparison operators can be used in conditional statements to compare values and take action depending on the result:
if (age<18) document.write("Too young");
You will learn more about the use of conditional statements in the next chapter of this tutorial.
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Logical Operators
Logical operators are used to determine the logic between variables or values.
Given that x=6 and y=3, the table below explains the logical operators:
Operator Description Example
&& and (x < 10 && y > 1) is true
|| or (x==5 || y==5) is false
! not !(x==y) is true
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Conditional Operator
JavaScript also contains a conditional operator that assigns a value to a variable based on some condition.
Syntax
variablename=(condition)?value1:value2
Example
greeting=(visitor=="PRES")?"Dear President ":"Dear ";
If the variable visitor has the value of "PRES", then the variable greeting will be assigned the value "Dear President " else it will be assigned "Dear".
--------------------------------------------------------------------------------
Comparison and Logical operators are used to test for true or false.
--------------------------------------------------------------------------------
Comparison Operators
Comparison operators are used in logical statements to determine equality or difference between variables or values.
Given that x=5, the table below explains the comparison operators:
Operator Description Example
== is equal to x==8 is false
=== is exactly equal to (value and type) x===5 is true
x==="5" is false
!= is not equal x!=8 is true
> is greater than x>8 is false
< is less than x<8 is true
>= is greater than or equal to x>=8 is false
<= is less than or equal to x<=8 is true
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How Can it be Used
Comparison operators can be used in conditional statements to compare values and take action depending on the result:
if (age<18) document.write("Too young");
You will learn more about the use of conditional statements in the next chapter of this tutorial.
--------------------------------------------------------------------------------
Logical Operators
Logical operators are used to determine the logic between variables or values.
Given that x=6 and y=3, the table below explains the logical operators:
Operator Description Example
&& and (x < 10 && y > 1) is true
|| or (x==5 || y==5) is false
! not !(x==y) is true
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Conditional Operator
JavaScript also contains a conditional operator that assigns a value to a variable based on some condition.
Syntax
variablename=(condition)?value1:value2
Example
greeting=(visitor=="PRES")?"Dear President ":"Dear ";
If the variable visitor has the value of "PRES", then the variable greeting will be assigned the value "Dear President " else it will be assigned "Dear".