diff --git a/types/peerjs/index.d.ts b/types/peerjs/index.d.ts
index 4ca88fd50b..faf99dc9b3 100644
--- a/types/peerjs/index.d.ts
+++ b/types/peerjs/index.d.ts
@@ -2,9 +2,7 @@
 // Project: http://peerjs.com/
 // Definitions by: Toshiya Nakakura <https://github.com/nakakura>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
-// TypeScript Version: 2.3
-
-/// <reference types="webrtc" />
+// TypeScript Version: 3.2
 
 declare namespace PeerJs{
     interface PeerJSOption{
@@ -13,7 +11,7 @@ declare namespace PeerJs{
         port?: number;
         path?: string;
         secure?: boolean;
-        config?: RTCPeerConnectionConfig;
+        config?: RTCConfiguration;
         debug?: number;
     }
 
diff --git a/types/skyway/index.d.ts b/types/skyway/index.d.ts
index eb73937178..e396f8cff0 100644
--- a/types/skyway/index.d.ts
+++ b/types/skyway/index.d.ts
@@ -2,9 +2,7 @@
 // Project: http://nttcom.github.io/skyway/
 // Definitions by: Toshiya Nakakura <https://github.com/nakakura>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
-// TypeScript Version: 2.3
-
-/// <reference types="webrtc" />
+// TypeScript Version: 3.2
 
 declare namespace PeerJs{
     interface PeerJSOption{
@@ -14,7 +12,7 @@ declare namespace PeerJs{
         path?: string;
         secure?: boolean;
         turn?: boolean;
-        config?: RTCPeerConnectionConfig;
+        config?: RTCConfiguration;
         debug?: number;
     }
 
diff --git a/types/w3c-generic-sensor/index.d.ts b/types/w3c-generic-sensor/index.d.ts
index 40f6db6301..bec987d04f 100644
--- a/types/w3c-generic-sensor/index.d.ts
+++ b/types/w3c-generic-sensor/index.d.ts
@@ -2,12 +2,10 @@
 // Project: https://www.w3.org/TR/generic-sensor/
 // Definitions by: Kenneth Rohde Christiansen <https://github.com/kenchris>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
-// TypeScript Version: 2.2
+// TypeScript Version: 3.2
 
 // Explainer: https://www.w3.org/TR/motion-sensors/
 
-/// <reference types="geometry-dom" />
-
 declare class SensorErrorEvent extends Event {
     constructor(type: string, errorEventInitDict: SensorErrorEventInit);
     readonly error: Error;
@@ -82,7 +80,7 @@ declare class UncalibratedMagnetometer extends Sensor {
 
 // Orientation Sensor: https://www.w3.org/TR/orientation-sensor/
 
-type RotationMatrixType = Float32Array | Float64Array | GeometryDom.DOMMatrix;
+type RotationMatrixType = Float32Array | Float64Array | DOMMatrix;
 
 declare class OrientationSensor extends Sensor {
     readonly quaternion?: number[];
diff --git a/types/w3c-screen-orientation/index.d.ts b/types/w3c-screen-orientation/index.d.ts
index 7cac6c33f3..74fee2ecb6 100644
--- a/types/w3c-screen-orientation/index.d.ts
+++ b/types/w3c-screen-orientation/index.d.ts
@@ -2,8 +2,8 @@
 // Project: https://www.w3.org/TR/screen-orientation/
 // Definitions by: Kenneth Rohde Christiansen <https://github.com/kenchris>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 3.2
 
-type OrientationType = "portrait-primary" | "portrait-secondary" | "landscape-primary" | "landscape-secondary";
 type ScreenOrientationLockType = "any" | "natural" | "landscape" | "portrait" | "portrait-primary" | "portrait-secondary" | "landscape-primary" | "landscape-secondary";
 
 interface ScreenOrientation extends EventTarget {
diff --git a/types/web-animations-js/index.d.ts b/types/web-animations-js/index.d.ts
index 54c0b8c01b..c317675727 100644
--- a/types/web-animations-js/index.d.ts
+++ b/types/web-animations-js/index.d.ts
@@ -2,10 +2,10 @@
 // Project: https://github.com/web-animations/web-animations-js
 // Definitions by: Kristian Moerch <https://github.com/kritollm>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 3.2
 
 type AnimationEffectTimingFillMode = "none" | "forwards" | "backwards" | "both" | "auto";
 type AnimationEffectTimingPlaybackDirection = "normal" | "reverse" | "alternate" | "alternate-reverse";
-type AnimationPlayState = "idle" | "running" | "paused" | "finished";
 
 interface AnimationPlaybackEvent {
     target: Animation;
@@ -68,18 +68,7 @@ interface ComputedTimingProperties {
     currentIteration: number | null;
 }
 
-declare class KeyframeEffect implements AnimationEffectReadOnly {
-    constructor(target: HTMLElement, effect: AnimationKeyFrame | AnimationKeyFrame[], timing: number | AnimationEffectTiming, id?: string);
-    activeDuration: number;
-    onsample: (timeFraction: number | null, effect: KeyframeEffect, animation: Animation) => void | undefined;
-    parent: KeyframeEffect | null;
-    target: HTMLElement;
-    timing: number;
-    getComputedTiming(): ComputedTimingProperties;
-    getFrames(): AnimationKeyFrame[];
-    remove(): void;
-}
-type AnimationEventListener = (this: Animation, evt: AnimationPlaybackEvent) => any;
+type AnimationEventListener = ((this: Animation, evt: AnimationPlaybackEvent) => any) | null;
 
 interface Animation extends EventTarget {
     currentTime: number | null;
@@ -88,7 +77,7 @@ interface Animation extends EventTarget {
     onfinish: AnimationEventListener;
     readonly playState: AnimationPlayState;
     playbackRate: number;
-    startTime: number;
+    startTime: number | null;
     cancel(): void;
     finish(): void;
     pause(): void;
@@ -96,15 +85,15 @@ interface Animation extends EventTarget {
     reverse(): void;
     addEventListener(type: "finish" | "cancel", handler: EventListener): void;
     removeEventListener(type: "finish" | "cancel", handler: EventListener): void;
-    effect: AnimationEffectReadOnly;
+    effect: AnimationEffect | null;
     readonly finished: Promise<Animation>;
     readonly ready: Promise<Animation>;
-    timeline: AnimationTimeline;
+    timeline: AnimationTimeline | null;
 }
 
 declare var Animation: {
     prototype: Animation;
-    new(effect?: AnimationEffectReadOnly, timeline?: AnimationTimeline): Animation;
+    new(effect?: AnimationEffect | null, timeline?: AnimationTimeline | null): Animation;
 };
 
 declare class SequenceEffect extends KeyframeEffect {
@@ -118,5 +107,5 @@ interface Element {
     getAnimations(): Animation[];
 }
 interface Document {
-    timeline: AnimationTimeline;
+    readonly timeline: AnimationTimeline;
 }
diff --git a/types/webrtc/RTCPeerConnection.d.ts b/types/webrtc/RTCPeerConnection.d.ts
index 210ab66ddd..4b5c1cea53 100644
--- a/types/webrtc/RTCPeerConnection.d.ts
+++ b/types/webrtc/RTCPeerConnection.d.ts
@@ -2,6 +2,7 @@
 // Project: https://www.w3.org/TR/webrtc/
 // Definitions by: Danilo Bargen <https://github.com/dbrgn/>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 3.2
 //
 // W3 Spec: https://www.w3.org/TR/webrtc/
 //
@@ -11,8 +12,6 @@
 
 /// <reference path='MediaStream.d.ts' />
 
-type EventHandler = (event: Event) => void;
-
 // https://www.w3.org/TR/webrtc/#idl-def-rtcofferansweroptions
 interface RTCOfferAnswerOptions {
     voiceActivityDetection?: boolean; // default = true
@@ -28,10 +27,10 @@ interface RTCAnswerOptions extends RTCOfferAnswerOptions {
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcpeerconnectionstate
-type RTCPeerConnectionState = 'new' | 'connecting' | 'connected' | 'disconnected' | 'failed' | 'closed';
+// type RTCPeerConnectionState = 'new' | 'connecting' | 'connected' | 'disconnected' | 'failed' | 'closed';
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcicecredentialtype
-type RTCIceCredentialType = 'password' | 'token';
+// type RTCIceCredentialType = 'password' | 'token';
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtciceserver
 interface RTCIceServer {
@@ -40,7 +39,7 @@ interface RTCIceServer {
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtcpmuxpolicy
-type RTCRtcpMuxPolicy = 'negotiate' | 'require';
+// type RTCRtcpMuxPolicy = 'negotiate' | 'require';
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtciceparameters
 interface RTCIceParameters {
@@ -49,6 +48,7 @@ interface RTCIceParameters {
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcicetransport
+type IceTransportEventHandler = ((this: RTCIceTransport, ev: Event) => any) | null;
 interface RTCIceTransport {
     //readonly role: RTCIceRole;
     //readonly component: RTCIceComponent;
@@ -59,17 +59,18 @@ interface RTCIceTransport {
     getSelectedCandidatePair(): RTCIceCandidatePair | null;
     getLocalParameters(): RTCIceParameters | null;
     getRemoteParameters(): RTCIceParameters | null;
-    onstatechange: EventHandler;
-    ongatheringstatechange: EventHandler;
-    onselectedcandidatepairchange: EventHandler;
+    onstatechange: IceTransportEventHandler;
+    ongatheringstatechange: IceTransportEventHandler;
+    onselectedcandidatepairchange: IceTransportEventHandler;
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcdtlstransport
+type DtlsTransportEventHandler = ((this: RTCDtlsTransport, ev: Event) => any) | null;
 interface RTCDtlsTransport {
     readonly transport: RTCIceTransport;
     //readonly state: RTCDtlsTransportState;
     getRemoteCertificates(): ArrayBuffer[];
-    onstatechange: EventHandler;
+    onstatechange: DtlsTransportEventHandler;
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtpcodeccapability
@@ -79,7 +80,7 @@ interface RTCRtpCodecCapability {
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtpheaderextensioncapability
 interface RTCRtpHeaderExtensionCapability {
-    uri: string;
+    uri?: string;
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtpcapabilities
@@ -99,17 +100,17 @@ interface RTCRtpFecParameters {
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcdtxstatus
-type RTCDtxStatus = 'disabled' | 'enabled';
+// type RTCDtxStatus = 'disabled' | 'enabled';
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcprioritytype
-type RTCPriorityType = 'very-low' | 'low' | 'medium' | 'high';
+// type RTCPriorityType = 'very-low' | 'low' | 'medium' | 'high';
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtpencodingparameters
 interface RTCRtpEncodingParameters {
     //ssrc: number;
     //rtx: RTCRtpRtxParameters;
     //fec: RTCRtpFecParameters;
-    dtx: RTCDtxStatus;
+    dtx?: RTCDtxStatus;
     //active: boolean;
     //priority: RTCPriorityType;
     //maxBitrate: number;
@@ -121,7 +122,7 @@ interface RTCRtpEncodingParameters {
 interface RTCRtpHeaderExtensionParameters {
     //uri: string;
     //id: number;
-    encrypted: boolean;
+    encrypted?: boolean;
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtcpparameters
@@ -136,7 +137,7 @@ interface RTCRtpCodecParameters {
     mimeType: string;
     //clockRate: number;
     channels?: number; // default = 1
-    sdpFmtpLine: string;
+    sdpFmtpLine?: string;
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtpparameters
@@ -152,9 +153,9 @@ interface RTCRtpParameters {
 // https://www.w3.org/TR/webrtc/#dom-rtcrtpcontributingsource
 interface RTCRtpContributingSource {
     //readonly timestamp: number;
-    readonly source: number;
+    source: number;
     //readonly audioLevel: number | null;
-    readonly voiceActivityFlag: boolean | null;
+    readonly voiceActivityFlag?: boolean | undefined;
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtpcapabilities
@@ -183,7 +184,7 @@ interface RTCRtpReceiver {
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtptransceiverdirection
-type RTCRtpTransceiverDirection = 'sendrecv' | 'sendonly' | 'recvonly' | 'inactive';
+// type RTCRtpTransceiverDirection = 'sendrecv' | 'sendonly' | 'recvonly' | 'inactive';
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtptransceiver
 interface RTCRtpTransceiver {
@@ -191,7 +192,7 @@ interface RTCRtpTransceiver {
     readonly sender: RTCRtpSender;
     readonly receiver: RTCRtpReceiver;
     readonly stopped: boolean;
-    readonly direction: RTCRtpTransceiverDirection;
+    direction: RTCRtpTransceiverDirection;
     setDirection(direction: RTCRtpTransceiverDirection): void;
     stop(): void;
     setCodecPreferences(codecs: RTCRtpCodecCapability[]): void;
@@ -200,8 +201,8 @@ interface RTCRtpTransceiver {
 // https://www.w3.org/TR/webrtc/#idl-def-rtcrtptransceiverinit
 interface RTCRtpTransceiverInit {
     direction?: RTCRtpTransceiverDirection; // default = 'sendrecv'
-    streams: MediaStream[];
-    sendEncodings: RTCRtpEncodingParameters[];
+    streams?: MediaStream[];
+    sendEncodings?: RTCRtpEncodingParameters[];
 }
 
 // https://www.w3.org/TR/webrtc/#dom-rtccertificate
@@ -241,12 +242,13 @@ interface RTCDataChannelInit {
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcdatachannelstate
-type RTCDataChannelState = 'connecting' | 'open' | 'closing' | 'closed';
+// type RTCDataChannelState = 'connecting' | 'open' | 'closing' | 'closed';
 
 // https://www.w3.org/TR/websockets/#dom-websocket-binarytype
-type RTCBinaryType = 'blob' | 'arraybuffer';
+// type RTCBinaryType = 'blob' | 'arraybuffer';
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcdatachannel
+type DataChannelEventHandler<E extends Event> = ((this: RTCDataChannel, ev: E) => any) | null;
 interface RTCDataChannel extends EventTarget {
     readonly label: string;
     readonly ordered: boolean;
@@ -254,33 +256,33 @@ interface RTCDataChannel extends EventTarget {
     readonly maxRetransmits: number | null;
     readonly protocol: string;
     readonly negotiated: boolean;
-    readonly id: number;
+    readonly id: number | null;
     readonly readyState: RTCDataChannelState;
     readonly bufferedAmount: number;
     bufferedAmountLowThreshold: number;
-    binaryType: RTCBinaryType;
+    binaryType: string;
 
     close(): void;
     send(data: string | Blob | ArrayBuffer | ArrayBufferView): void;
 
-    onopen: EventHandler;
-    onmessage: (event: MessageEvent) => void;
-    onbufferedamountlow: EventHandler;
-    onerror: (event: ErrorEvent) => void;
-    onclose: EventHandler;
+    onopen: DataChannelEventHandler<Event>;
+    onmessage: DataChannelEventHandler<MessageEvent>;
+    onbufferedamountlow: DataChannelEventHandler<Event>;
+    onerror: DataChannelEventHandler<RTCErrorEvent>;
+    onclose: DataChannelEventHandler<Event>;
 }
 
 // https://www.w3.org/TR/webrtc/#h-rtctrackevent
 interface RTCTrackEvent extends Event {
     readonly receiver: RTCRtpReceiver;
     readonly track: MediaStreamTrack;
-    readonly streams: MediaStream[];
+    readonly streams: ReadonlyArray<MediaStream>;
     readonly transceiver: RTCRtpTransceiver;
 }
 
 // https://www.w3.org/TR/webrtc/#h-rtcpeerconnectioniceevent
 interface RTCPeerConnectionIceEvent extends Event {
-    readonly url: string;
+    readonly url: string | null;
 }
 
 // https://www.w3.org/TR/webrtc/#h-rtcpeerconnectioniceerrorevent
@@ -297,6 +299,7 @@ interface RTCDataChannelEvent {
 }
 
 // https://www.w3.org/TR/webrtc/#idl-def-rtcpeerconnection
+type PeerConnectionEventHandler<E extends Event> = ((this: RTCPeerConnection, ev: E) => any) | null;
 interface RTCPeerConnection extends EventTarget {
     createOffer(options?: RTCOfferOptions): Promise<RTCSessionDescriptionInit>;
     createAnswer(options?: RTCAnswerOptions): Promise<RTCSessionDescriptionInit>;
@@ -320,8 +323,8 @@ interface RTCPeerConnection extends EventTarget {
     setConfiguration(configuration: RTCConfiguration): void;
     close(): void;
 
-    onicecandidateerror: (event: RTCPeerConnectionIceErrorEvent) => void;
-    onconnectionstatechange: EventHandler;
+    onicecandidateerror: PeerConnectionEventHandler<RTCPeerConnectionIceErrorEvent>;
+    onconnectionstatechange: PeerConnectionEventHandler<Event>;
 
     // Extension: https://www.w3.org/TR/webrtc/#h-rtcpeerconnection-interface-extensions
     getSenders(): RTCRtpSender[];
@@ -330,12 +333,12 @@ interface RTCPeerConnection extends EventTarget {
     addTrack(track: MediaStreamTrack, ...streams: MediaStream[]): RTCRtpSender;
     removeTrack(sender: RTCRtpSender): void;
     addTransceiver(trackOrKind: MediaStreamTrack | string, init?: RTCRtpTransceiverInit): RTCRtpTransceiver;
-    ontrack: (event: RTCTrackEvent) => void;
+    ontrack: PeerConnectionEventHandler<RTCTrackEvent>;
 
     // Extension: https://www.w3.org/TR/webrtc/#h-rtcpeerconnection-interface-extensions-1
     readonly sctp: RTCSctpTransport | null;
     createDataChannel(label: string | null, dataChannelDict?: RTCDataChannelInit): RTCDataChannel;
-    ondatachannel: (event: RTCDataChannelEvent) => void;
+    ondatachannel: PeerConnectionEventHandler<RTCDataChannelEvent>;
 
     // Extension: https://www.w3.org/TR/webrtc/#h-rtcpeerconnection-interface-extensions-2
     getStats(selector?: MediaStreamTrack | null): Promise<RTCStatsReport>;