API Reference

Class: ParameterWatcher

ROS2.0 JavaScript client with Node.js

class

ParameterWatcher(node, remoteNodeName, parameterNames, optionsopt)

ParameterWatcher - Watches parameter changes on a remote node Subscribes to /parameter_events and emits 'change' events when watched parameters on the target node are modified.
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Extends

  • EventEmitter

Members

member

(readonly) remoteNodeName :string

Get the remote node name being watched.
Type:
  • string
Source:
member

(readonly) watchedParameters :Array.<string>

Get the list of watched parameter names.
Type:
  • Array.<string>
Source:

Methods

function

addParameter(name)

Add a parameter name to the watch list.
Parameters:
Name Type Description
name string Parameter name to watch
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Throws:
  • If name is not a string
    Type TypeError
  • If the watcher has been destroyed
    Type Error
function

destroy()

Destroy the watcher and clean up resources. Unsubscribes from parameter events and destroys the parameter client.
Source:
function

(async) getCurrentValues(optionsopt) → {Promise.<Array.<Parameter>>}

Get current values of all watched parameters.
Parameters:
Name Type Attributes Description
options object <optional>
 Options for the parameter client
Properties
Name Type Attributes Description
timeout number <optional>
 Timeout in milliseconds
signal AbortSignal <optional>
 AbortSignal for cancellation
Source:
Throws:
If the watcher has been destroyed
Type Error
Returns:
Array of Parameter objects
Type Promise.<Array.<Parameter>>
function

isDestroyed() → {boolean}

Check if the watcher has been destroyed.
Source:
Returns:
True if destroyed
Type boolean
function

removeParameter(name) → {boolean}

Remove a parameter name from the watch list.
Parameters:
Name Type Description
name string Parameter name to stop watching
Source:
Throws:
If the watcher has been destroyed
Type Error
Returns:
True if the parameter was in the watch list
Type boolean
function

(async) start(timeoutopt) → {Promise.<boolean>}

Start watching for parameter changes. Waits for the remote node's parameter services and subscribes to parameter events.
Parameters:
Name Type Attributes Default Description
timeout number <optional>
 5000 Timeout in milliseconds to wait for services
Source:
Throws:
If the watcher has been destroyed
Type Error
Returns:
Resolves to true when watching has started
Type Promise.<boolean>