Pencil Code Reference > click

click respond to a mouse click

click is an event-handler function. When a user clicks on the screen with the mouse, a function is called and an action is performed.

Syntax

click (e) -> 
    #line 1
  #line 2
  #line 3
  #...

• e is the location the mouse was clicked. This can be used as a location in commands such as moveto, jumpto, turnto, etc.

click preforms like a regular function, but it cannot be called within the code and cannot be given a specific input. It is only called when the user clicks the mouse. The corresponding action can be anything you like, e.g. exit a program, run a script, draw something.

In this example, clicking on the screen moves the turtle to the position that was clicked.

Notice that we have specified speed Infinity in order to keep up with the speed of the mouse clicks.

  speed Infinity
  click (e) -> moveto e

But click does not have to use the location of the mouse at all.

The following example counts the number of times the mouse is clicked, regardless of location.

speed Infinity
ht()
a = 0
dot lightblue, 10000
label a, { fontSize: 60, fontFamily: "Consolas" }
click ->
  cs()
  dot lightblue, 10000
  a += 1
  label a, { fontSize: 60, fontFamily: "Consolas" }

Note that, in the above example, if you click fast enough, you can actually select the label. This is because a label is actually an HTML element, just like the rest of the text on this page.