Variables have a global or function "
scope". For example, variables declared within either the
setup() or
draw() functions may be only used in these functions. Global variables, variables declared outside of
setup() and
draw(), may be used anywhere within the program. If a function variable is declared with the same name as a global variable, the program will use the function variable to make its calculations within the current scope.
let a = 80; // Create a global variable "a"
function setup() {
createCanvas(720, 400);
background(0);
stroke(255);
noLoop();
}
function draw() {
// Draw a line using the global variable "a"
line(a, 0, a, height);
// Use a local variable a in for loop
for (let a = 120; a < 200; a += 3) {
line(a, 0, a, height);
}
// Make a call to the custom function drawAnotherLine()
drawAnotherLine();
// Make a call to the custom function drawYetAnotherLine()
drawYetAnotherLine();
}
function drawAnotherLine() {
// Create a new variable "a" local to this function
let a = 320;
// Draw a line using the local variable "a"
line(a, 0, a, height);
}
function drawYetAnotherLine() {
// Because no new local variable "a" is set,
// this line draws using the original global
// variable "a" which is set to the value 20.
line(a + 3, 0, a + 3, height);
}​
