Tutorial: Introduction to JavaScript

Operators

comparison

==	"Equal to" returns true if operands are equal.
===	Strict equality "Equal to" -- JavaScript 1.3+ only
!=	"Not equal to" returns true if operands are not equal.
!==	Strict equality "Not equal to" -- JavaScript 1.3+ only
>	"Greater than" returns true if left operand is greater than right operand.
>=	"Greater than or equal to" returns true if left operand is greater than or equal to right operand.
<	"Less than" returns true if left operand is less than right operand.
<=	"Less than or equal to" returns true if left operand is less than or equal to right operand.

The precise comparisons made using these operators varies between versions of JavaScript. In both JavaScript 1.3 and JavaScript 1.1 or earlier, these comparison operators perform a "type conversion" if necessary. In other words, if one operand is a string value and the other is a numeric value, JavaScript attempts to convert the string to numeric before performing the comparison (for instance, the string "5" would convert to the number 5).

In contrast, JavaScript 1.2 does not perform type conversion, and so if the two operands are of different types they cannot be legitimately compared. Finally, JavaScript 1.3+ also adds "strict equality" operators, === and !== (note the double equal signs). With a strict equality operator, the comparison will only yield a result if the two operands are of the same type.