allow JSON.stringify(context)

Tone/core/context/BaseContext.ts

@@ -8,63 +8,90 @@ type Transport = import("../clock/Transport").Transport;
 type Listener = import("./Listener").Listener;
 
 // these are either not used in Tone.js or deprecated and not implemented.
-export type ExcludedFromBaseAudioContext = "onstatechange" | "addEventListener" | "removeEventListener" | "listener" | "dispatchEvent" | "audioWorklet" | "destination" | "createScriptProcessor";
+export type ExcludedFromBaseAudioContext =
+	| "onstatechange"
+	| "addEventListener"
+	| "removeEventListener"
+	| "listener"
+	| "dispatchEvent"
+	| "audioWorklet"
+	| "destination"
+	| "createScriptProcessor";
 
 // the subset of the BaseAudioContext which Tone.Context implements.
-export type BaseAudioContextSubset = Omit<BaseAudioContext, ExcludedFromBaseAudioContext>;
+export type BaseAudioContextSubset = Omit<
+	BaseAudioContext,
+	ExcludedFromBaseAudioContext
+>;
 
 export type ContextLatencyHint = AudioContextLatencyCategory;
 
-export abstract class BaseContext extends Emitter<"statechange" | "tick"> implements BaseAudioContextSubset {
+export abstract class BaseContext
-
+	extends Emitter<"statechange" | "tick">
+	implements BaseAudioContextSubset {
 	//---------------------------
 	// BASE AUDIO CONTEXT METHODS
 	//---------------------------
-	abstract createAnalyser(): AnalyserNode
+	abstract createAnalyser(): AnalyserNode;
 
-	abstract createOscillator(): OscillatorNode
+	abstract createOscillator(): OscillatorNode;
 
-	abstract createBufferSource(): AudioBufferSourceNode
+	abstract createBufferSource(): AudioBufferSourceNode;
 
-	abstract createBiquadFilter(): BiquadFilterNode
+	abstract createBiquadFilter(): BiquadFilterNode;
 
-	abstract createBuffer(_numberOfChannels: number, _length: number, _sampleRate: number): AudioBuffer
+	abstract createBuffer(
+		_numberOfChannels: number,
+		_length: number,
+		_sampleRate: number
+	): AudioBuffer;
 
-	abstract createChannelMerger(_numberOfInputs?: number | undefined): ChannelMergerNode
+	abstract createChannelMerger(
+		_numberOfInputs?: number | undefined
+	): ChannelMergerNode;
 
-	abstract createChannelSplitter(_numberOfOutputs?: number | undefined): ChannelSplitterNode
+	abstract createChannelSplitter(
+		_numberOfOutputs?: number | undefined
+	): ChannelSplitterNode;
 
-	abstract createConstantSource(): ConstantSourceNode
+	abstract createConstantSource(): ConstantSourceNode;
 
-	abstract createConvolver(): ConvolverNode
+	abstract createConvolver(): ConvolverNode;
 
-	abstract createDelay(_maxDelayTime?: number | undefined): DelayNode
+	abstract createDelay(_maxDelayTime?: number | undefined): DelayNode;
 
-	abstract createDynamicsCompressor(): DynamicsCompressorNode
+	abstract createDynamicsCompressor(): DynamicsCompressorNode;
 
-	abstract createGain(): GainNode
+	abstract createGain(): GainNode;
 
-	abstract createIIRFilter(_feedForward: number[] | Float32Array, _feedback: number[] | Float32Array): IIRFilterNode
+	abstract createIIRFilter(
+		_feedForward: number[] | Float32Array,
+		_feedback: number[] | Float32Array
+	): IIRFilterNode;
 
-	abstract createPanner(): PannerNode
+	abstract createPanner(): PannerNode;
 
 	abstract createPeriodicWave(
 		_real: number[] | Float32Array,
 		_imag: number[] | Float32Array,
-		_constraints?: PeriodicWaveConstraints | undefined,
+		_constraints?: PeriodicWaveConstraints | undefined
-	): PeriodicWave
+	): PeriodicWave;
 
-	abstract createStereoPanner(): StereoPannerNode
+	abstract createStereoPanner(): StereoPannerNode;
 
-	abstract createWaveShaper(): WaveShaperNode
+	abstract createWaveShaper(): WaveShaperNode;
 
-	abstract createMediaStreamSource(_stream: MediaStream): MediaStreamAudioSourceNode
+	abstract createMediaStreamSource(
+		_stream: MediaStream
+	): MediaStreamAudioSourceNode;
 
-	abstract createMediaElementSource(_element: HTMLMediaElement): MediaElementAudioSourceNode
+	abstract createMediaElementSource(
+		_element: HTMLMediaElement
+	): MediaElementAudioSourceNode;
 
-	abstract createMediaStreamDestination(): MediaStreamAudioDestinationNode
+	abstract createMediaStreamDestination(): MediaStreamAudioDestinationNode;
 
-	abstract decodeAudioData(_audioData: ArrayBuffer): Promise<AudioBuffer>
+	abstract decodeAudioData(_audioData: ArrayBuffer): Promise<AudioBuffer>;
 
 	//---------------------------
 	// TONE AUDIO CONTEXT METHODS
@@ -73,45 +100,56 @@ export abstract class BaseContext extends Emitter<"statechange" | "tick"> implem
 	abstract createAudioWorkletNode(
 		_name: string,
 		_options?: Partial<AudioWorkletNodeOptions>
-	): AudioWorkletNode
+	): AudioWorkletNode;
 
-	abstract get rawContext(): AnyAudioContext
+	abstract get rawContext(): AnyAudioContext;
 
-	abstract async addAudioWorkletModule(_url: string, _name: string): Promise<void>
+	abstract async addAudioWorkletModule(
+		_url: string,
+		_name: string
+	): Promise<void>;
 
 	abstract lookAhead: number;
 
 	abstract latencyHint: ContextLatencyHint | Seconds;
 
-	abstract resume(): Promise<void>
+	abstract resume(): Promise<void>;
 
-	abstract setTimeout(_fn: (...args: any[]) => void, _timeout: Seconds): number
+	abstract setTimeout(
+		_fn: (...args: any[]) => void,
+		_timeout: Seconds
+	): number;
 
-	abstract clearTimeout(_id: number): this
+	abstract clearTimeout(_id: number): this;
 
-	abstract setInterval(_fn: (...args: any[]) => void, _interval: Seconds): number
+	abstract setInterval(
+		_fn: (...args: any[]) => void,
+		_interval: Seconds
+	): number;
 
-	abstract clearInterval(_id: number): this
+	abstract clearInterval(_id: number): this;
 
-	abstract getConstant(_val: number): AudioBufferSourceNode
+	abstract getConstant(_val: number): AudioBufferSourceNode;
 
-	abstract get currentTime(): Seconds
+	abstract get currentTime(): Seconds;
 
-	abstract get state(): AudioContextState
+	abstract get state(): AudioContextState;
 
-	abstract get sampleRate(): number
+	abstract get sampleRate(): number;
 
-	abstract get listener(): Listener
+	abstract get listener(): Listener;
 
-	abstract get transport(): Transport
+	abstract get transport(): Transport;
 
-	abstract get draw(): Draw
+	abstract get draw(): Draw;
 
-	abstract get destination(): Destination
+	abstract get destination(): Destination;
 
-	abstract now(): Seconds
+	abstract now(): Seconds;
 
-	abstract immediate(): Seconds
+	abstract immediate(): Seconds;
+
+	abstract toJSON(): Record<string, any>;
 
 	readonly isOffline: boolean = false;
 }

Tone/core/context/Context.test.ts

@@ -12,7 +12,6 @@ import { Draw } from "../util/Draw";
 import { connect } from "./ToneAudioNode";
 
 describe("Context", () => {
-
 	it("creates and disposes the classes attached to the context", async () => {
 		const ac = createAudioContext();
 		const context = new Context(ac);
@@ -32,7 +31,6 @@ describe("Context", () => {
 	});
 
 	context("AudioContext", () => {
-
 		it("extends the AudioContext methods", () => {
 			const ctx = new Context(createAudioContext());
 			expect(ctx).to.have.property("createGain");
@@ -46,8 +44,15 @@ describe("Context", () => {
 			return ctx.close();
 		});
 
+		it("can be stringified", () => {
+			const ctx = new Context(createAudioContext());
+			expect(JSON.stringify(ctx)).to.equal("{}");
+			ctx.dispose();
+			return ctx.close();
+		});
+
 		if (ONLINE_TESTING) {
-			it("clock is running", done => {
+			it("clock is running", (done) => {
 				const interval = setInterval(() => {
 					if (getContext().currentTime > 0.5) {
 						clearInterval(interval);
@@ -88,7 +93,6 @@ describe("Context", () => {
 	});
 
 	context("state", () => {
-
 		it("can suspend and resume the state", async () => {
 			const ac = createAudioContext();
 			const context = new Context(ac);
@@ -105,14 +109,14 @@ describe("Context", () => {
 			const ac = createAudioContext();
 			const context = new Context(ac);
 			let triggerChange = false;
-			context.on("statechange", state => {
+			context.on("statechange", (state) => {
 				if (!triggerChange) {
 					triggerChange = true;
 					expect(state).to.equal("running");
 				}
 			});
 			await context.resume();
-			await new Promise(done => setTimeout(() => done(), 10));
+			await new Promise((done) => setTimeout(() => done(), 10));
 			expect(triggerChange).to.equal(true);
 			context.dispose();
 			return ac.close();
@@ -120,9 +124,7 @@ describe("Context", () => {
 	});
 
 	if (ONLINE_TESTING) {
-
 		context("clockSource", () => {
-
 			let ctx;
 			beforeEach(() => {
 				ctx = new Context();
@@ -138,14 +140,14 @@ describe("Context", () => {
 				expect(ctx.clockSource).to.equal("worker");
 			});
 
-			it("provides callback", done => {
+			it("provides callback", (done) => {
 				expect(ctx.clockSource).to.equal("worker");
 				ctx.setTimeout(() => {
 					done();
 				}, 0.1);
 			});
 
-			it("can be set to 'timeout'", done => {
+			it("can be set to 'timeout'", (done) => {
 				ctx.clockSource = "timeout";
 				expect(ctx.clockSource).to.equal("timeout");
 				ctx.setTimeout(() => {
@@ -153,7 +155,7 @@ describe("Context", () => {
 				}, 0.1);
 			});
 
-			it("can be set to 'offline'", done => {
+			it("can be set to 'offline'", (done) => {
 				ctx.clockSource = "offline";
 				expect(ctx.clockSource).to.equal("offline");
 				// provides no callback
@@ -167,9 +169,7 @@ describe("Context", () => {
 		});
 	}
 	context("setTimeout", () => {
-
 		if (ONLINE_TESTING) {
-
 			let ctx;
 			beforeEach(() => {
 				ctx = new Context();
@@ -181,19 +181,19 @@ describe("Context", () => {
 				return ctx.close();
 			});
 
-			it("can set a timeout", done => {
+			it("can set a timeout", (done) => {
 				ctx.setTimeout(() => {
 					done();
 				}, 0.1);
 			});
 
 			it("returns an id", () => {
-				expect(ctx.setTimeout(() => { }, 0.1)).to.be.a("number");
+				expect(ctx.setTimeout(() => {}, 0.1)).to.be.a("number");
 				// try clearing a random ID, shouldn't cause any errors
 				ctx.clearTimeout(-2);
 			});
 
-			it("timeout is not invoked when cancelled", done => {
+			it("timeout is not invoked when cancelled", (done) => {
 				const id = ctx.setTimeout(() => {
 					throw new Error("shouldn't be invoked");
 				}, 0.01);
@@ -203,7 +203,7 @@ describe("Context", () => {
 				}, 0.02);
 			});
 
-			it("order is maintained", done => {
+			it("order is maintained", (done) => {
 				let wasInvoked = false;
 				ctx.setTimeout(() => {
 					expect(wasInvoked).to.equal(true);
@@ -216,7 +216,7 @@ describe("Context", () => {
 		}
 
 		it("is invoked in the offline context", () => {
-			return Offline(context => {
+			return Offline((context) => {
 				const transport = new Transport({ context });
 				transport.context.setTimeout(() => {
 					expect(transport.now()).to.be.closeTo(0.01, 0.005);
@@ -226,9 +226,7 @@ describe("Context", () => {
 	});
 
 	context("setInterval", () => {
-
 		if (ONLINE_TESTING) {
-
 			let ctx;
 			beforeEach(() => {
 				ctx = new Context();
@@ -240,19 +238,19 @@ describe("Context", () => {
 				return ctx.close();
 			});
 
-			it("can set an interval", done => {
+			it("can set an interval", (done) => {
 				ctx.setInterval(() => {
 					done();
 				}, 0.1);
 			});
 
 			it("returns an id", () => {
-				expect(ctx.setInterval(() => { }, 0.1)).to.be.a("number");
+				expect(ctx.setInterval(() => {}, 0.1)).to.be.a("number");
 				// try clearing a random ID, shouldn't cause any errors
 				ctx.clearInterval(-2);
 			});
 
-			it("timeout is not invoked when cancelled", done => {
+			it("timeout is not invoked when cancelled", (done) => {
 				const id = ctx.setInterval(() => {
 					throw new Error("shouldn't be invoked");
 				}, 0.01);
@@ -262,7 +260,7 @@ describe("Context", () => {
 				}, 0.02);
 			});
 
-			it("order is maintained", done => {
+			it("order is maintained", (done) => {
 				let wasInvoked = false;
 				ctx.setInterval(() => {
 					expect(wasInvoked).to.equal(true);
@@ -276,7 +274,7 @@ describe("Context", () => {
 
 		it("is invoked in the offline context", () => {
 			let invocationCount = 0;
-			return Offline(context => {
+			return Offline((context) => {
 				context.setInterval(() => {
 					invocationCount++;
 				}, 0.01);
@@ -287,10 +285,13 @@ describe("Context", () => {
 
 		it("is invoked in with the right interval", () => {
 			let numberOfInvocations = 0;
-			return Offline(context => {
+			return Offline((context) => {
 				let intervalTime = context.now();
 				context.setInterval(() => {
-					expect(context.now() - intervalTime).to.be.closeTo(0.01, 0.005);
+					expect(context.now() - intervalTime).to.be.closeTo(
+						0.01,
+						0.005
+					);
 					intervalTime = context.now();
 					numberOfInvocations++;
 				}, 0.01);
@@ -301,7 +302,6 @@ describe("Context", () => {
 	});
 
 	context("get/set", () => {
-
 		let ctx;
 		beforeEach(() => {
 			ctx = new Context();
@@ -324,7 +324,7 @@ describe("Context", () => {
 		});
 
 		it("gets a constant signal", () => {
-			return ConstantOutput(context => {
+			return ConstantOutput((context) => {
 				const bufferSrc = context.getConstant(1);
 				connect(bufferSrc, context.destination);
 			}, 1);
@@ -335,7 +335,6 @@ describe("Context", () => {
 			const bufferB = ctx.getConstant(2);
 			expect(bufferA).to.equal(bufferB);
 		});
-
 	});
 
 	context("Methods", () => {

Tone/core/context/Context.ts

@@ -4,7 +4,11 @@ import { isAudioContext } from "../util/AdvancedTypeCheck";
 import { optionsFromArguments } from "../util/Defaults";
 import { Timeline } from "../util/Timeline";
 import { isDefined, isString } from "../util/TypeCheck";
-import { AnyAudioContext, createAudioContext, createAudioWorkletNode } from "./AudioContext";
+import {
+	AnyAudioContext,
+	createAudioContext,
+	createAudioWorkletNode,
+} from "./AudioContext";
 import { closeContext, initializeContext } from "./ContextInitialization";
 import { BaseContext, ContextLatencyHint } from "./BaseContext";
 import { assert } from "../util/Debug";
@@ -33,7 +37,6 @@ export interface ContextTimeoutEvent {
  * @category Core
  */
 export class Context extends BaseContext {
-
 	readonly name: string = "Context";
 
 	/**
@@ -107,7 +110,9 @@ export class Context extends BaseContext {
 	constructor(options?: Partial<ContextOptions>);
 	constructor() {
 		super();
-		const options = optionsFromArguments(Context.getDefaults(), arguments, ["context"]);
+		const options = optionsFromArguments(Context.getDefaults(), arguments, [
+			"context",
+		]);
 
 		if (options.context) {
 			this._context = options.context;
@@ -117,7 +122,11 @@ export class Context extends BaseContext {
 			});
 		}
 
-		this._ticker = new Ticker(this.emit.bind(this, "tick"), options.clockSource, options.updateInterval);
+		this._ticker = new Ticker(
+			this.emit.bind(this, "tick"),
+			options.clockSource,
+			options.updateInterval
+		);
 		this.on("tick", this._timeoutLoop.bind(this));
 
 		// fwd events from the context
@@ -166,13 +175,21 @@ export class Context extends BaseContext {
 	createBiquadFilter(): BiquadFilterNode {
 		return this._context.createBiquadFilter();
 	}
-	createBuffer(numberOfChannels: number, length: number, sampleRate: number): AudioBuffer {
+	createBuffer(
+		numberOfChannels: number,
+		length: number,
+		sampleRate: number
+	): AudioBuffer {
 		return this._context.createBuffer(numberOfChannels, length, sampleRate);
 	}
-	createChannelMerger(numberOfInputs?: number | undefined): ChannelMergerNode {
+	createChannelMerger(
+		numberOfInputs?: number | undefined
+	): ChannelMergerNode {
 		return this._context.createChannelMerger(numberOfInputs);
 	}
-	createChannelSplitter(numberOfOutputs?: number | undefined): ChannelSplitterNode {
+	createChannelSplitter(
+		numberOfOutputs?: number | undefined
+	): ChannelSplitterNode {
 		return this._context.createChannelSplitter(numberOfOutputs);
 	}
 	createConstantSource(): ConstantSourceNode {
@@ -190,7 +207,10 @@ export class Context extends BaseContext {
 	createGain(): GainNode {
 		return this._context.createGain();
 	}
-	createIIRFilter(feedForward: number[] | Float32Array, feedback: number[] | Float32Array): IIRFilterNode {
+	createIIRFilter(
+		feedForward: number[] | Float32Array,
+		feedback: number[] | Float32Array
+	): IIRFilterNode {
 		// @ts-ignore
 		return this._context.createIIRFilter(feedForward, feedback);
 	}
@@ -200,7 +220,7 @@ export class Context extends BaseContext {
 	createPeriodicWave(
 		real: number[] | Float32Array,
 		imag: number[] | Float32Array,
-		constraints?: PeriodicWaveConstraints | undefined,
+		constraints?: PeriodicWaveConstraints | undefined
 	): PeriodicWave {
 		return this._context.createPeriodicWave(real, imag, constraints);
 	}
@@ -211,17 +231,28 @@ export class Context extends BaseContext {
 		return this._context.createWaveShaper();
 	}
 	createMediaStreamSource(stream: MediaStream): MediaStreamAudioSourceNode {
-		assert(isAudioContext(this._context), "Not available if OfflineAudioContext");
+		assert(
+			isAudioContext(this._context),
+			"Not available if OfflineAudioContext"
+		);
 		const context = this._context as AudioContext;
 		return context.createMediaStreamSource(stream);
 	}
-	createMediaElementSource(element: HTMLMediaElement): MediaElementAudioSourceNode {
+	createMediaElementSource(
-		assert(isAudioContext(this._context), "Not available if OfflineAudioContext");
+		element: HTMLMediaElement
+	): MediaElementAudioSourceNode {
+		assert(
+			isAudioContext(this._context),
+			"Not available if OfflineAudioContext"
+		);
 		const context = this._context as AudioContext;
 		return context.createMediaElementSource(element);
 	}
 	createMediaStreamDestination(): MediaStreamAudioDestinationNode {
-		assert(isAudioContext(this._context), "Not available if OfflineAudioContext");
+		assert(
+			isAudioContext(this._context),
+			"Not available if OfflineAudioContext"
+		);
 		const context = this._context as AudioContext;
 		return context.createMediaStreamDestination();
 	}
@@ -256,7 +287,10 @@ export class Context extends BaseContext {
 		return this._listener;
 	}
 	set listener(l) {
-		assert(!this._initialized, "The listener cannot be set after initialization.");
+		assert(
+			!this._initialized,
+			"The listener cannot be set after initialization."
+		);
 		this._listener = l;
 	}
 
@@ -268,7 +302,10 @@ export class Context extends BaseContext {
 		return this._transport;
 	}
 	set transport(t: Transport) {
-		assert(!this._initialized, "The transport cannot be set after initialization.");
+		assert(
+			!this._initialized,
+			"The transport cannot be set after initialization."
+		);
 		this._transport = t;
 	}
 
@@ -292,7 +329,10 @@ export class Context extends BaseContext {
 		return this._destination;
 	}
 	set destination(d: Destination) {
-		assert(!this._initialized, "The destination cannot be set after initialization.");
+		assert(
+			!this._initialized,
+			"The destination cannot be set after initialization."
+		);
 		this._destination = d;
 	}
 
@@ -303,7 +343,7 @@ export class Context extends BaseContext {
 	/**
 	 * Maps a module name to promise of the addModule method
 	 */
-	private _workletModules: Map<string, Promise<void>> = new Map()
+	private _workletModules: Map<string, Promise<void>> = new Map();
 
 	/**
 	 * Create an audio worklet node from a name and options. The module
@@ -322,9 +362,15 @@ export class Context extends BaseContext {
 	 * @param name The name of the module
 	 */
 	async addAudioWorkletModule(url: string, name: string): Promise<void> {
-		assert(isDefined(this.rawContext.audioWorklet), "AudioWorkletNode is only available in a secure context (https or localhost)");
+		assert(
+			isDefined(this.rawContext.audioWorklet),
+			"AudioWorkletNode is only available in a secure context (https or localhost)"
+		);
 		if (!this._workletModules.has(name)) {
-			this._workletModules.set(name, this.rawContext.audioWorklet.addModule(url));
+			this._workletModules.set(
+				name,
+				this.rawContext.audioWorklet.addModule(url)
+			);
 		}
 		await this._workletModules.get(name);
 	}
@@ -334,7 +380,7 @@ export class Context extends BaseContext {
 	 */
 	protected async workletsAreReady(): Promise<void> {
 		const promises: Promise<void>[] = [];
-		this._workletModules.forEach(promise => promises.push(promise));
+		this._workletModules.forEach((promise) => promises.push(promise));
 		await Promise.all(promises);
 	}
 
@@ -465,7 +511,11 @@ export class Context extends BaseContext {
 		if (this._constants.has(val)) {
 			return this._constants.get(val) as AudioBufferSourceNode;
 		} else {
-			const buffer = this._context.createBuffer(1, 128, this._context.sampleRate);
+			const buffer = this._context.createBuffer(
+				1,
+				128,
+				this._context.sampleRate
+			);
 			const arr = buffer.getChannelData(0);
 			for (let i = 0; i < arr.length; i++) {
 				arr[i] = val;
@@ -488,7 +538,9 @@ export class Context extends BaseContext {
 		super.dispose();
 		this._ticker.dispose();
 		this._timeouts.dispose();
-		Object.keys(this._constants).map(val => this._constants[val].disconnect());
+		Object.keys(this._constants).map((val) =>
+			this._constants[val].disconnect()
+		);
 		return this;
 	}
 
@@ -536,7 +588,7 @@ export class Context extends BaseContext {
 	 * @param  id  The ID returned from setTimeout
 	 */
 	clearTimeout(id: number): this {
-		this._timeouts.forEach(event => {
+		this._timeouts.forEach((event) => {
 			if (event.id === id) {
 				this._timeouts.remove(event);
 			}
@@ -573,4 +625,13 @@ export class Context extends BaseContext {
 		intervalFn();
 		return id;
 	}
+
+	/*
+	 * This is a placeholder so that JSON.stringify does not throw an error
+	 * This matches what JSON.stringify(audioContext) returns on a native
+	 * audioContext instance.
+	 */
+	toJSON() {
+		return {};
+	}
 }

Tone/core/context/DummyContext.ts

@@ -8,7 +8,6 @@ type Transport = import("../clock/Transport").Transport;
 type Listener = import("./Listener").Listener;
 
 export class DummyContext extends BaseContext {
-
 	//---------------------------
 	// BASE AUDIO CONTEXT METHODS
 	//---------------------------
@@ -28,15 +27,23 @@ export class DummyContext extends BaseContext {
 		return {} as BiquadFilterNode;
 	}
 
-	createBuffer(_numberOfChannels: number, _length: number, _sampleRate: number): AudioBuffer {
+	createBuffer(
+		_numberOfChannels: number,
+		_length: number,
+		_sampleRate: number
+	): AudioBuffer {
 		return {} as AudioBuffer;
 	}
 
-	createChannelMerger(_numberOfInputs?: number | undefined): ChannelMergerNode {
+	createChannelMerger(
+		_numberOfInputs?: number | undefined
+	): ChannelMergerNode {
 		return {} as ChannelMergerNode;
 	}
 
-	createChannelSplitter(_numberOfOutputs?: number | undefined): ChannelSplitterNode {
+	createChannelSplitter(
+		_numberOfOutputs?: number | undefined
+	): ChannelSplitterNode {
 		return {} as ChannelSplitterNode;
 	}
 
@@ -60,7 +67,10 @@ export class DummyContext extends BaseContext {
 		return {} as GainNode;
 	}
 
-	createIIRFilter(_feedForward: number[] | Float32Array, _feedback: number[] | Float32Array): IIRFilterNode {
+	createIIRFilter(
+		_feedForward: number[] | Float32Array,
+		_feedback: number[] | Float32Array
+	): IIRFilterNode {
 		return {} as IIRFilterNode;
 	}
 
@@ -71,7 +81,7 @@ export class DummyContext extends BaseContext {
 	createPeriodicWave(
 		_real: number[] | Float32Array,
 		_imag: number[] | Float32Array,
-		_constraints?: PeriodicWaveConstraints | undefined,
+		_constraints?: PeriodicWaveConstraints | undefined
 	): PeriodicWave {
 		return {} as PeriodicWave;
 	}
@@ -88,7 +98,9 @@ export class DummyContext extends BaseContext {
 		return {} as MediaStreamAudioSourceNode;
 	}
 
-	createMediaElementSource(_element: HTMLMediaElement): MediaElementAudioSourceNode {
+	createMediaElementSource(
+		_element: HTMLMediaElement
+	): MediaElementAudioSourceNode {
 		return {} as MediaElementAudioSourceNode;
 	}
 
@@ -170,12 +182,12 @@ export class DummyContext extends BaseContext {
 	get draw(): Draw {
 		return {} as Draw;
 	}
-	set draw(_d) { }
+	set draw(_d) {}
 
 	get destination(): Destination {
 		return {} as Destination;
 	}
-	set destination(_d: Destination) { }
+	set destination(_d: Destination) {}
 
 	now() {
 		return 0;
@@ -185,5 +197,9 @@ export class DummyContext extends BaseContext {
 		return 0;
 	}
 
+	toJSON() {
+		return {};
+	}
+
 	readonly isOffline: boolean = false;
 }