HTML and CSS Reference
In-Depth Information
and Compound Statements
If you were confronted with the above signpost, you'd have to decide which direction to
take. People control their lives by making decisions, and so do programs. In fact, accord-
ing to computer science topics, a good language allows you to control the flow of your
program in three ways. It lets you
•
Execute a sequence of statements.
•
Branch to an alternative sequence of statements, based on a test.
•
Repeat a sequence of statements until some condition is met.
Well, then JavaScript must be a good language. We've already used programs that exe-
cute a sequence of statements, one after another.
Now we will examine the branching and looping control structures that allow the
flow of the program's control to change depending on some conditional expression.
The decision-making constructs (
if
,
if/else
,
if/else if
,
switch
) contain a control expres-
sion that determines whether a block of statements will be executed. The looping con-
structs (
while, for
) allow the program to execute a statement block repetitively until
some condition is satisfied.
A compound statement or block consists of a group of statements surrounded by
curly braces. The block is syntactically equivalent to a single statement and usually fol-
lows an
if
,
else
,
while
, or
for
construct.
Conditional constructs control the flow of a program. If a condition is true, the program
will execute a block of statements and if the condition is false, flow will go to an alter-
nate block of statements. Decision-making constructs (
if, else, switch
) contain a control
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