Page 101 - DCAP202_Fundamentals of Web Programming

Fundamentals of Web Programming

Notes It should be noted that you aren’t limited to using a variable with a static, unchanging value.
You may use a variable that changes dynamically with either user driven or script driven
actions associated with it to obtain a changing value.

Self Assessment

Fill in the blanks:
1. ........................... Statements give the JavaScript code you are writing the ability to make
decisions or perform single or multiple tasks.

2. The ........................... conditional statement is used to perform an action “if” the condition
is met.
3. The ........................... conditional statement is used to test all of the possible outcomes for
the application you are designing.

8.2 Looping Statements

Often when you write code, you want the same block of code to run over and over again in a
row. Instead of adding several almost equal lines in a script we can use loops to perform a task
like this.

In JavaScript, there are two different kinds of loops:
 for - loops through a block of code a specified number of times
 while - loops through a block of code while a specified condition is true

8.2.1 The For Loop

The for loop is used when you know in advance how many times the script should run. Some
important points to note are:
 The initialization statements are executed once; only when the for loop is encountered.
 After execution of initialization statements, the condition is evaluated.

 After every iteration, the updation statements are executed and then the condition is
checked
Syntax
for (var=startvalue;var<=endvalue;var=var+increment)
{
code to be executed
}

!
Caution The increment parameter could also be negative, and the <= could be any comparing
statement.

Example: Loop example
The example below defines a loop that starts with i=0. The loop will continue to run as long as
i is less than, or equal to 5. i will increase by 1 each time the loop runs.

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