pxt-calliope/docs/javascript/call.md

Call a function

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

basic.showString("Hello!")

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

This feature is known as "Intellisense". 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:

You can type anything to see what Intellisense will find for you. Here's an example of what happens when you type the word for:

Function parameter values

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

basic.showString("Hello!",50)

Intellisense shows all the available parameters for a function.

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 in order to call the function. For example

basic.clearScreen()

It's a syntax error to have a left parenthesis without the "closing" right parenthesis:

basic.clearScreen(

~button /javascript/sequence

NEXT: Sequencing Commands

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