67 lines
2.1 KiB
Markdown
67 lines
2.1 KiB
Markdown
|
# Function Parameters
|
||
|
|
|
||
|
|
How to use parameters to pass info in and out of an function. #docs #input #output #function #functionparameters
|
||
|
|
|
||
|
|
### @parent js/function
|
||
|
|
|
||
|
|
|
||
|
|
A [function](/microbit/js/function) can have multiple input parameters and/or a single output parameter. The parameters must be one of the supported variable [types](/microbit/js/types).
|
||
|
|
|
||
|
|
When you first [create a function](/microbit/js/function), it looks like this:
|
||
|
|
```
|
||
|
|
export function doStuff() {
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
### Add a function parameter
|
||
|
|
|
||
|
|
1. Open your script (if needed) and then click `script` in the upper-right corner.
|
||
|
|
|
||
|
|
2. Under **code** click your function name.
|
||
|
|
|
||
|
|
3. Click the function name in your code (this opens the function panel).
|
||
|
|
|
||
|
|
4. Click **add input parameter** or **add output parameter**. The parameter is added to your function.
|
||
|
|
|
||
|
|
#### Input parameters
|
||
|
|
|
||
|
|
The default type for an input parameter is [Number](/microbit/reference/types/number):
|
||
|
|
|
||
|
|
```
|
||
|
|
export function oneInput(p: number) {
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
To change the default type, click the type ([Number](/microbit/reference/types/number) in this case) and change it to [String](/microbit/reference/types/string), [Boolean](/microbit/reference/types/boolean), or [Image](/microbit/reference/image/image). You can add multiple input parameters to a function.
|
||
|
|
|
||
|
|
#### Output parameter
|
||
|
|
|
||
|
|
the default type for an output parameter is [Number](/microbit/reference/types/number):
|
||
|
|
|
||
|
|
```
|
||
|
|
export function output() : number {
|
||
|
|
let r: number
|
||
|
|
return 42
|
||
|
|
return r
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
To change the default type, click the type ([Number](/microbit/reference/types/number) in this case) and change it to [String](/microbit/reference/types/string), [Boolean](/microbit/reference/types/boolean), or [Image](/microbit/reference/image/image).
|
||
|
|
|
||
|
|
### Inputs and output function
|
||
|
|
|
||
|
|
The following sample function has two inputs and one output parameter (all are the Number type):
|
||
|
|
|
||
|
|
```
|
||
|
|
export function inputsAndOutput(p: number, q: number) : number {
|
||
|
|
let r: number
|
||
|
|
return p + q
|
||
|
|
return r
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
### See also
|
||
|
|
|
||
|
|
[call a function](/microbit/js/call), [create a function](/microbit/js/function), [return](/microbit/js/return)
|
||
|
|
|