Repeating Things¶
Imagine you want to draw a hundred circles. It would be too cumbersome to write 100 lines of code to do circles.
The For Loop¶
The following example draws concentric circles
function draw() {
for (var d=10; d<50; d=d+10) {
circle(400, 400, d);
}
}
The for loop is a construct available in the Javascript programming language to loop over a sequence of numbers.
A for loop will of the following form:
for (initial_state; loop_condition; increment) {
body
}
The for loop continues to execute the body repeatedly as long the loop_condition is satisified. Each execution is called as as iteration.
A loop typically have a loop variable and the initial_state specifies the initial value for the loop variable.
In our example, the loop variable is d, representing the diameter of the circle that we want to draw and is initialized to 10.
The loop_condition specifies the condition that must be satisified for the loop to continue. In our example,
we want to continue the loop as long as the value of d is less than 400.
The increment specifies how should the loop variable change after each iteration of the loop. In our example,
we want to incrent d by 10.
When we run the program, it will draw 4 concentric circles with diameter 10, 20, 30 and 40.
Notice that it will not draw cicle with diameter 50 as the condition is d < 50 and not d <= 50.
You can change the value from 50 to 500 to get lot more concentric circles.
