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    JavaScript Comparison and Logical Operators

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    تاريخ التسجيل : 16/02/2011

    JavaScript Comparison and Logical Operators

    مُساهمة  Admin في الثلاثاء فبراير 22, 2011 5:13 pm

    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".

      الوقت/التاريخ الآن هو الجمعة نوفمبر 24, 2017 10:28 pm