Note Class

The Note class represents a single musical note with expressions defining its properties.

Constructor

const note = new Note(id, variables = {})

Parameters

Name	Type	Description
id	number	Unique note identifier
variables	object	Initial expression strings

WARNING

Notes should be created via module.addNote(), not directly.

Properties

id

note.id  // number (read-only)

Unique identifier. BaseNote has ID 0, other notes have positive IDs.

expressions

note.expressions  // object

Map of property names to BinaryExpression objects:

{
  startTime: BinaryExpression,
  duration: BinaryExpression,
  frequency: BinaryExpression,
  tempo: BinaryExpression,
  beatsPerMeasure: BinaryExpression,
  measureLength: BinaryExpression
}

properties

note.properties  // object

Non-expression properties:

{
  color: string | null,      // CSS color
  instrument: string | null  // Instrument name
}

parentId

note.parentId  // number | null

Optional parent note ID for hierarchical organization.

Variable Access

getVariable()

const value = note.getVariable(name)

Returns the evaluated value from the module's cache.

Parameter	Type	Description
name	string	Property name

Returns: Fraction object.

Example:

const freq = note.getVariable('frequency')  // Fraction
freq.valueOf()  // 440 (JavaScript number)

setVariable()

note.setVariable(name, value)

Sets an expression or property.

Parameter	Type	Description
name	string	Property name
value	string	Expression text (for expressions) or value (for properties)

Example:

// Set expression
note.setVariable('frequency', "module.baseNote.getVariable('frequency').mul(new Fraction(2))")

// Set property
note.setVariable('color', '#ff0000')

getExpressionSource()

const source = note.getExpressionSource(name)
// → "module.baseNote.getVariable('frequency').mul(new Fraction(3, 2))"

Returns the original expression text.

getExpression()

const expr = note.getExpression(name)
// → BinaryExpression

Returns the compiled BinaryExpression object.

hasExpression()

const has = note.hasExpression(name)
// → boolean

Checks if an expression is defined.

getAllVariables()

const all = note.getAllVariables()
// → { startTime: Fraction, duration: Fraction, frequency: Fraction, ... }

Returns all evaluated values.

Dependency Tracking

getAllDependencies()

const deps = note.getAllDependencies()
// → Set<number>

Returns IDs of all notes referenced in any expression.

referencesBaseNote()

const refs = note.referencesBaseNote()
// → boolean

Checks if any expression references the BaseNote.

Expression Properties

Property	Type	Description
startTime	Fraction	When note plays (seconds)
duration	Fraction	How long note plays (seconds)
frequency	Fraction	Pitch in Hz
tempo	Fraction	Tempo in BPM
beatsPerMeasure	Fraction	Time signature numerator
measureLength	Fraction	Computed measure duration

Non-Expression Properties

Property	Type	Description
color	string	CSS color for visualization
instrument	string	Instrument name

Internal Methods

_setExpression()

note._setExpression(name, exprText)

Compiles expression and notifies module.

_setExpressionSilent()

note._setExpressionSilent(name, exprText)

Sets expression without notification (used in batch operations).

_notifyChange()

note._notifyChange()

Triggers module cache invalidation and event emission.

Serialization

toJSON()

const json = note.toJSON()
// → { id, frequency, startTime, duration, color, instrument, ... }

Serializes note with expression source text.

Example Usage

// Create via module
const note = module.addNote({
  frequency: "module.baseNote.getVariable('frequency').mul(new Fraction(5, 4))",
  startTime: "new Fraction(0)",
  duration: "new Fraction(60).div(module.findTempo(module.baseNote))"
})

// Set color
note.setVariable('color', '#4a90d9')

// Change frequency
note.setVariable('frequency', "module.baseNote.getVariable('frequency').mul(new Fraction(3, 2))")

// Read values (after evaluation)
const freq = note.getVariable('frequency')
console.log(freq.valueOf())  // 660

// Check dependencies
const deps = note.getAllDependencies()
console.log(deps.has(0))  // true (references BaseNote)

// Get source
const source = note.getExpressionSource('frequency')
console.log(source)  // "module.baseNote.getVariable('frequency').mul(new Fraction(3, 2))"

See Also

• Module Class - Module API
• BinaryExpression - Expression objects
• Creating Notes - User guide