Using Javascript booleans

Using Javascript booleans.

  • The boolean datatype has only two possible values which is true or false.
  • The boolean value is for the most the result of comparisons you make in your JavaScript programs.
  • Any program code is meant to do some actions based on conditions.
  • These conditions is normally based on an evaluation of values using relational operators which in Javascript are:
    Operator Example Comments
    ==
    (equality)
    '50'==50 // true
     30 ==50 // false
    Returns true when both operands are equal. The operands are converted to the same type before being compared.
    !=
    (non-equality)
    '50'!=50 // false
     30 !=50 // true
    Returns true when both operands are not equal. The operands are converted to the same type before being compared.
    ===
    (equality)
    '50'===50 // false
     50 ===50 // true
    Returns true if both operands are equal and of the same type.
    !==
    (non-equality)
    '50'!==50 // true
     50 !==50 // false
    Returns true if both operands are not equal and of the same type.
    >
    (greater than)
    '50'>40 // true
     50 >50 // false
    Returns true if the left operand is greater than the right one.
    >=
    (greater than or equal)
    '50'>=50 // true
     30 >=50 // false
    Returns true if the left operand is greater than or equal to the right one.
    <
    (less than)
    '50'<40 // false
     50 <50 // false
    Returns true if the left operand is greater than the right one.
    <=
    (less than or equal)
    '50'<=50 // false
     50 <=50 // true
    Returns true if the left operand is greater than or equal to the right one.
  • In such evaluation we can use some Logical Operators as well:
    Name Operator Sample Description
    AND && expession1 && expression2 Both expressions must return true if the outcome shall be true
    OR || expession1 || expression2 One of the expressions must return true if the outcome shall be true
    NOT ! !expression If the expression return false the outcome will be true

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