The Conditional Operators
The conditional operators are a way of testing for specific
conditions: equality, identity, relational, and logical. Though the
processes may differ, and they range from simple to complex, the result
of using such operators is one of two values: true
or false
.
The Equality and the Identity (String Equality) Operators
One of the most common operators used in a conditional expression is the equality operator, ==. It is used when a variable is compared with another variable or literal value, and based on the result, an action or set of actions is triggered:
// at some point in application, assign 3 to variable nValue var nValue = 3; ... if (nValue == 3) ...
In this example, if the variable nValue
is equal to 3, what follows
(represented by the ellipses in the text) is processed. Otherwise, the
flow of the program skips over the code block and goes to the first
statement following.
Warning
Be careful not to leave off the second equals sign (=). If you
do, the expression becomes one of assignment, not conditional
testing. The variable nValue
is
assigned the value of 3. Since the assignment was successful, it
returns true
. It always returns
true
. A JavaScript error doesnât
occur, and as such, it may be hard to spot this error in
debugging.
As with the addition operator, the equality operator converts the variableâs data type to facilitate the evaluation of the expression. If one value is numeric and the other is string, comparing both is successful if the value ...
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