|| (Logical OR) : Boolean Operators « Operators « JavaScript Tutorial






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The logical OR operator in JavaScript is the same as in Java, using the double pipe (||):

var bTrue = true;
var bFalse = false;
var bResult = bTrue || bFalse;

Logical OR behaves as described in the following truth table:

Operand 1Operand 2Result
truetruetrue
truefalsetrue
falsetruetrue
falsefalsefalse


Just like logical AND, if either operand is not a Boolean, logical OR will not always return a Boolean value:

If one operand is an object and one is a Boolean, the object is returned.

If both operands are objects, the first operand is returned.

If both operands are null, null is returned.

If either operand is NaN, NaN is returned.

If either operand is undefined, an error occurs.

<html>
    <script language="JavaScript">
    <!--
    x = 8;
    if((8==x) || (x=7))
    {
      document.write("The || evaluated TRUE!<br>");
    }
    else
    {
      document.write("The || evaluated FALSE!<br>");
    }
    document.write("x=",x,"<br>");
    -->
    </script>
    </html>








2.6.Boolean Operators
2.6.1.JavaScript provides three Boolean operators
2.6.2.Logical AND
2.6.3.! (Logical NOT)
2.6.4.Use logical NOT to control the loop
2.6.5.|| (Logical OR)