>=
greater or equal
x >= 2
<
less
x < 2
<=
less or equal
x <= 2
Loops
With loops it is possible to repeatedly execute parts of the script. There are two kinds of loops:
1. For loop: This is normally used if the number of repetitions is fixed or known in a variable.
The for loop is started with the keyword for, followed by three expressions within parenthesis
and a statement block within {}:
for (initial-expression; condition; increment-expression)
{
statements
}
The initial-expression initializes the counting variable, the condition defines when the
loop is to be finished, the increment-expression is used to increment the counting variable in
each cycle of the loop.
2. While loop: The number of repetitions need not be known at the time of writing the script, the
loop is terminated by a condition which is usually calculated at the time when the script is
executed only. The syntax is similar to an if statement: The keyword while is followed by a
condition and a statement block within {}:
while (condition)
{
statements
}
With the keyword break the loops can be terminated at any time. When break is excuted, the loop is
aborted and script execution continues after the loop code block.
With the keyword continue, the code inside a loop can be skipped. When continue is excuted, the
script immediately continues
Arrays
Arrays are used to store several values in one variable. There are two ways to create an array variable:
1. via the new keyword: var TestArray = new Array(); or var TestArray = new Array(1,
2, 3, 4);
2. via square brackets: var TestArray2 = [1, 2, 3, 4];
The values are stored in the array by using an index, starting with 0 for the first entry in the array. The
length of an array is determinded dynamically: It is the index + 1 of the last defined value in the array.
Values in the arra can be of all available data types: numbers, strings, even other arrays
Several operations are possible on arrays:
– length property: get the number of elements in the array
– square brackets []: set or retrieve values by index
– toString(): gets a text representation of all values
– push(value): add value to the end of the array
– pop(): retrieve and remove last value
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