The multiply operator is *.

<!DOCTYPE html>
    <script type="text/javascript">
        var result = 3 * 5; 
        document.writeln(result); //15

Click to view the demo

If either of the operands isn't a number, it is converted to a number using the Number() casting function. An empty string is treated as 0, and the Boolean value of true is treated as 1.

The multiply operator has the following behaviors:

numbernumberregular arithmetic multiplication, may have result of Number.NEGATIVE_INFINITY or Number.POSITIVE_INFINITY
any valueNaNNaN
NaNany valueNaN
Infinityany finite number other than 0Number.NEGATIVE_INFINITY or Number.POSITIVE_INFINITY depending on the sign of the second operand
  JavaScript Book 
    Language Basics  

  1. JavaScript Operators
  2. Increment/Decrement Operators
  3. Increment/Decrement Operators for String, Boolean, Floating-point and Object
  4. Unary Plus and Minus
  5. Bitwise Not operator
  6. Bitwise AND
  7. Bitwise OR
  8. Bitwise XOR
  9. Left Shift
  10. Signed Right Shift
  11. Unsigned Right Shift
  12. Logical NOT
  13. Logical AND
  14. Logical OR
  15. Multiply
  16. Divide
  17. Modulus
  18. Add
  19. Subtract
  20. Relational Operators
  21. Equal and Not Equal
  22. Identically Equal and Not Identically Equal
  23. Conditional Operator
  24. Assignment Operators
  25. Comma Operator