User Guide

Using operators to manipulate values in expressions 37

Equality operators

You can use the equality (

==) operator to determine whether the values or references of two

operands are equal. This comparison returns a Boolean (

true or false) value. If the operands are

strings, numbers, or Boolean values, they are compared by value. If the operands are objects or

arrays, they are compared by reference.

It is a common mistake to use the assignment operator to check for equality. For example, the

following code compares x to 2:

if (x == 2)

In that same example, the expression if (x = 2) would be incorrect, because it doesn’t compare

the operands; it assigns the value of 2 to the variable

The strict equality (

===) operator is similar to the equality operator, with one important

difference: The strict equality operator does not perform type conversion. If the two operands are

of different types, the strict equality operator returns

false. The strict inequality (!==) operator

returns the opposite of the strict equality operator.

The following table lists the ActionScript equality operators:

Assignment operators

You can use the assignment (

=) operator to assign a value to a variable, as shown in the

following example:

var password:String = "Sk8tEr";

You can also use the assignment operator to assign multiple variables in the same expression. In

the following statement, the value of

d is assigned to the variables a, b, and c:

a = b = c = d;

You can also use compound assignment operators to combine operations. Compound operators

perform on both operands and then assign the new value to the first operand. For example, the

following two statements are equivalent:

x += 15;

x = x + 15;

The assignment operator can also be used in the middle of an expression, as shown in the

following example:

// If the flavor is not vanilla, output a message.

if ((flavor = getIceCreamFlavor()) != "vanilla") {

trace ("Flavor was " + flavor + ", not vanilla.");

}

Operator Operation performed

Equality

===

Strict equality

Inequality

!==

Strict inequality