pxt-calliope/docs/js/call.md

Call a function

The simplest way to get started in JavaScript with your micro:bit is to call one of the micro:bit's built-in JavaScript functions. Just like Blocks are organized into categories/drawers, the micro:bit functions are organized by namespaces. The basic namespace contains a number of very helpful functions:

basic.showString("Hello!")

If you want to see all functions available in a namespace, simply type basic followed by .; a list of all the functions will appear.

Continue typing to select one of the functions, or click on one of the functions to select. You also narrow down the set of functions by typing, as below:

Function arguments

You might have noticed that the call showString above takes one argument, the string to be scrolled on the LED screen. There is a second (optional) argunment that controls the speed of the scroll. Try this:

basic.showString("Hello!",50)

If you don't give a value for an optional argument, where does its value come from?

Left and right parentheses, please!

Whenever you want to call a function, you give the name of the function followed by ( and ending with ). Inbetween the left and right parentheses go the function arguments. If a function has zero arguments, you still need the parentheses. For example

basic.clearScreen()

~button /js/sequence

NEXT: Sequencing Commands

~