=== and !== are strict comparison operators:
JavaScript has both strict and
type-converting equality comparison.
For strict equality the objects being
compared must have the same type and:
- Two strings are strictly equal when they have the same sequence of
characters, same length, and same
characters in corresponding positions.
- Two numbers are strictly equal when they are numerically equal (have
the same number value).
NaN is not
equal to anything, including NaN.
Positive and negative zeros are equal
to one another.
- Two Boolean operands are strictly equal if both are true or
both are false.
- Two objects are strictly equal if they refer to the same
Object.
Null and Undefined types are == (but not ===). [I.e. (Null==Undefined) is true but (Null===Undefined) is false]
Comparison Operators - MDC
