Using Javascript number operators.

Mathematical Number operators.

• To create numeric expressions we are using mathematical operators which can be:

  Operator	Example	Comments
  + (addition)	var sum1=50, sum2=30; var sum = sum1 + sum2; // sum will be 80	Used to add one operand with another operand.
  - (subtraction)	var sum1=50, sum2=30; var sum = sum1 - sum2; // sum will be 20	Used to subtract one operand with another operand.
  * (multiplication)	var price=10, quantity=5; var sum = price * quantity; // sum will be 50	Used to multiplicate one operand with another operand.
  / (division)	var price=10, sum=5; var quantity = sum / price; // quantity will be 0.5	Used to devide one operand with another operand.
  % (modulo)	var price=5, sum=11; var rest = sum % price; // rest will be 1	Used to get remainder from one operand with another operand.
  - (unary)	var sum2=11; var sum = -sum2; // sum will be -11	Converts a positive value to an equivalently negative value, and vice versa.
  + (unary)	var sum2=11; var sum = +sum2; // sum will be 11	The operator does nothing; it simply evaluates to the value of its argument.

• Expression can also be of incrementing and decrementing types:

   var count=10
   count++;              // Start with count and increment it. 
   count--;              // Start with count and decrement it. 
  // OR
   count = count + 1;    // Start with count and increment it with a value (1). 
   counter = count - 1;  // Start with count and decrement it with a value (1). 
  // OR
   count += 1;           // Start with count and increment it with a value (1).
   count -= 1;           // Start with count and decrement it with a value (1).

  The two first one has both two options which is prefix and postfix:

  var a = ++c;      // prefix operator - increments c and assign it to a
  var b = c++;      // postfix operator - assign c to b and then increment c
  var a = --c;      // prefix operator - decrements c and assign it to a
  var b = c--;      // postfix operator - assign c to b and then decrement c

  Program example using prefix and postfix with incrementing and decrementing:

  <script type="text/javascript">
    var value = 1;
    var result = value++ * 5;
    document.write("result: "+ result);
    document.write(" and value: "+  value);
    document.write("<br>");
    // prints: result: 5 and value: 2
    document.write("result: "+ --result);
    document.write(" and value: "+  value++);
    document.write("<br>");
    // prints: result: 4 and value: 2
    // but the result=4 and the value=3
    result = (++value * 5) ;
    document.write("result: "+ result);
    document.write(" and value: "+  value);
    document.write("<br>");
    // prints: result: 20 and value: 4
    document.write("result: "+ ++result);
    document.write(" and value: "+  --value);
    document.write("<br>");
    // prints: result: 21 and value: 3
  </script>