The JavaScript Diaries: Part 5 - Page 6
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The JavaScript Diaries: Part 5
Loops
Loops are used to repeat a process or section of code a specified number of
times. There are three types of loop statements: for
, while
,
and do while
. These statements use the increment/decrement
and comparison
operators we learned about previously.
The for
Statement
A for
statement is useful because it allows for the declaration of the variable, the condition for the statement, and the incremental expression all in one. The format of a for
statement is:
for (initialExpression; condition; incrementExpression) { statements }
|
Here is a sample for
statement. Be sure to try this yourself.
for (var newNum=1; newNum < 4; newNum++) { document.write("This pass is #" + newNum + "<br>"); }
Let's take a look at what's happening here.
|
The ++
increment operator is used to increase the value of the variable by one. You can also use the decrement operator, --
:
for (var newNum=9; newNum>4; newNum--) { document.write("This pass is #" + newNum + "
"); }
If you needed to increase/decrease the value of the variable by a different number, say 3, you would write it as: newNum+=3
or newNum-=3
, respectively.
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Created: June 10, 2005
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