Class: Script
The Script class is the fundamental base class for all scripts within Mirror Engine. It provides
the minimal interface required for a script to run.
At its core, a script is simply a collection of methods that are called at various points in the Engine's lifecycle. These methods are:
Script#initialize - Called once when the script is initialized Script#postInitialize - Called once after all scripts have been initialized Script#update - Called every frame, if the script is enabled Script#postUpdate - Called every frame, after all scripts have been updated Script#swap - Called when a script is redefined
These methods are entirely optional, but provide a useful way to manage the lifecycle of a script and perform any necessary setup and cleanup.
Below is a simple example of a script that rotates an entity every frame.
Example
class EntityRotator extends Script {
update() {
this.entity.rotateLocal(0, 1, 0)
}
}
When this script is attached to an entity, the update will be called every frame, slowly rotating the entity around the Y-axis.
Extends
Properties
app
app: AppBase
The AppBase that the instance of this type belongs to.
entity
entity: Entity
The Entity that the instance of this type belongs to.
enabled
Set Signature
set enabled(value: any): void
True if the instance of this type is in running state. False when script is not running,
because the Entity or any of its parents are disabled or the ScriptComponent is
disabled or the Script Instance is disabled. When disabled no update methods will be called
on each tick. initialize and postInitialize methods will run once when the script instance
is in enabled state during app tick.
Parameters
value
any
Returns
void
scriptName
Get Signature
get static scriptName(): null | string
Name of a Script Type.
Returns
null | string
Methods
fire()
fire(
name: string,
arg1?: any,
arg2?: any,
arg3?: any,
arg4?: any,
arg5?: any,
arg6?: any,
arg7?: any,
arg8?: any): EventHandler
Fire an event, all additional arguments are passed on to the event listener.
Parameters
name
string
Name of event to fire.
arg1?
any
First argument that is passed to the event handler.
arg2?
any
Second argument that is passed to the event handler.
arg3?
any
Third argument that is passed to the event handler.
arg4?
any
Fourth argument that is passed to the event handler.
arg5?
any
Fifth argument that is passed to the event handler.
arg6?
any
Sixth argument that is passed to the event handler.
arg7?
any
Seventh argument that is passed to the event handler.
arg8?
any
Eighth argument that is passed to the event handler.
Returns
Self for chaining.
Example
obj.fire('test', 'This is the message')
Inherited from
hasEvent()
hasEvent(name: string): boolean
Test if there are any handlers bound to an event name.
Parameters
name
string
The name of the event to test.
Returns
boolean
True if the object has handlers bound to the specified event name.
Example
obj.on('test', () => {}) // bind an event to 'test'
obj.hasEvent('test') // returns true
obj.hasEvent('hello') // returns false
Inherited from
off()
off(
name?: string,
callback?: HandleEventCallback,
scope?: any): EventHandler
Detach an event handler from an event. If callback is not provided then all callbacks are unbound from the event, if scope is not provided then all events with the callback will be unbound.
Parameters
name?
string
Name of the event to unbind.
callback?
HandleEventCallback
Function to be unbound.
scope?
any
Scope that was used as the this when the event is fired.
Returns
Self for chaining.
Example
const handler = () => {}
obj.on('test', handler)
obj.off() // Removes all events
obj.off('test') // Removes all events called 'test'
obj.off('test', handler) // Removes all handler functions, called 'test'
obj.off('test', handler, this) // Removes all handler functions, called 'test' with scope this
Inherited from
on()
on(
name: string,
callback: HandleEventCallback,
scope?: any): EventHandle
Attach an event handler to an event.
Parameters
name
string
Name of the event to bind the callback to.
callback
HandleEventCallback
Function that is called when event is fired. Note the callback is limited to 8 arguments.
scope?
any = ...
Object to use as 'this' when the event is fired, defaults to current this.
Returns
Can be used for removing event in the future.
Examples
obj.on('test', (a, b) => {
console.log(a + b)
})
obj.fire('test', 1, 2) // prints 3 to the console
const evt = obj.on('test', (a, b) => {
console.log(a + b)
})
// some time later
evt.off()
Inherited from
once()
once(
name: string,
callback: HandleEventCallback,
scope?: any): EventHandle
Attach an event handler to an event. This handler will be removed after being fired once.
Parameters
name
string
Name of the event to bind the callback to.
callback
HandleEventCallback
Function that is called when event is fired. Note the callback is limited to 8 arguments.
scope?
any = ...
Object to use as 'this' when the event is fired, defaults to current this.
Returns
- can be used for removing event in the future.
Example
obj.once('test', (a, b) => {
console.log(a + b)
})
obj.fire('test', 1, 2) // prints 3 to the console
obj.fire('test', 1, 2) // not going to get handled
Inherited from
Events
EVENT_ATTR
static EVENT_ATTR: string = 'attr';
Fired when script attributes have changed. This event is available in two forms. They are as follows:
attr- Fired for any attribute change. The handler is passed the name of the attribute that changed, the value of the attribute before the change and the value of the attribute after the change.attr:[name]- Fired for a specific attribute change. The handler is passed the value of the attribute before the change and the value of the attribute after the change.
Examples
export class PlayerController extends Script {
initialize() {
this.on('attr', (name, newValue, oldValue) => {
console.log(
`Attribute '${'${name}'}' changed from '${'${oldValue}'}' to '${'${newValue}'}'`
)
})
}
}
export class PlayerController extends Script {
initialize() {
this.on('attr:speed', (newValue, oldValue) => {
console.log(
`Attribute 'speed' changed from '${'${oldValue}'}' to '${'${newValue}'}'`
)
})
}
}
EVENT_DESTROY
static EVENT_DESTROY: string = 'destroy';
Fired when a script instance is destroyed and removed from component.
Example
export class PlayerController extends Script {
initialize() {
this.on('destroy', () => {
// no longer part of the entity
// this is a good place to clean up allocated resources used by the script
})
}
}
EVENT_DISABLE
static EVENT_DISABLE: string = 'disable';
Fired when a script instance becomes disabled.
Example
export class PlayerController extends Script {
initialize() {
this.on('disable', () => {
// Script Instance is now disabled
})
}
}
EVENT_ENABLE
static EVENT_ENABLE: string = 'enable';
Fired when a script instance becomes enabled.
Example
export class PlayerController extends Script {
initialize() {
this.on('enable', () => {
// Script Instance is now enabled
})
}
}
EVENT_ERROR
static EVENT_ERROR: string = 'error';
Fired when a script instance had an exception. The script instance will be automatically disabled. The handler is passed an Error object containing the details of the exception and the name of the method that threw the exception.
Example
export class PlayerController extends Script {
initialize() {
this.on('error', (err, method) => {
// caught an exception
console.log(err.stack)
})
}
}
EVENT_STATE
static EVENT_STATE: string = 'state';
Fired when a script instance changes state to enabled or disabled. The handler is passed a boolean parameter that states whether the script instance is now enabled or disabled.
Example
export class PlayerController extends Script {
initialize() {
this.on('state', (enabled) => {
console.log(`Script Instance is now ` + enabled)
})
}
}