How to use Subtract Operator in Javascript

Description

The subtract operator (-) is uses as follows:

The subtract operator has special rules as follows:

• If the two operands are numbers, do the subtract.
• If either operand is NaN, the result is NaN.
• For Infinity - Infinity, the result is NaN.
• For -Infinity - -Infinity, the result is NaN.
• If -Infinity is subtracted from Infinity, the result is Infinity.
• If Infinity is subtracted from -Infinity, the result is -Infinity.
• For +0 - +0, the result is +0.
• If -0 is subtracted from +0, the result is -0.
• For -0 - -0, the result is +0.
• If either operand is a string, a Boolean, null, or undefined, it is converted to a number using Number().
• If either operand is an object, its valueOf() method is called to retrieve a numeric value.
• If the object doesn't have valueOf() defined, then toString() is called and the resulting string is converted into a number.

Example

var result1 = 8 - true;    //true is converted to 1
console.log(result1);//from   w w w.  ja  v  a  2 s  .c o  m
var result2 = NaN - 1;     //NaN
console.log(result2);
var result3 = 8 - 3;       
console.log(result3);
var result4 = 8 - "";      //"" is converted to 0
console.log(result4);
var result5 = 8 - "2";     //"2" is converted to 2
console.log(result5);
var result6 = 8 - null;    //null is converted to 0
console.log(result6);

The code above generates the following result.