ElectronWebContents.once method

Unofficial

Registers a one-time listener for the before-input-event event.

Signature:

once(event: "before-input-event", listener: (event: ElectronEvent, input: ElectronInput) => void): this

Parameters:

Parameter	Type	Description
event	"before-input-event"	The event name.
listener	(event: ElectronEvent, input: ElectronInput) => void	Called when the `before-input-event` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the blur event.

Signature:

once(event: "blur", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"blur"	The event name.
listener	(...args: unknown[]) => void	Called when the `blur` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the certificate-error event.

Signature:

once(event: "certificate-error", listener: (event: ElectronEvent, url: string, error: string, certificate: ElectronCertificate, callback: (isTrusted: boolean) => void, isMainFrame: boolean) => void): this

Parameters:

Parameter	Type	Description
event	"certificate-error"	The event name.
listener	(event: ElectronEvent, url: string, error: string, certificate: ElectronCertificate, callback: (isTrusted: boolean) => void, isMainFrame: boolean) => void	Called when the `certificate-error` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the console-message event.

Signature:

once(event: "console-message", listener: (event: ElectronEvent, level: number, message: string, line: number, sourceId: string) => void): this

Parameters:

Parameter	Type	Description
event	"console-message"	The event name.
listener	(event: ElectronEvent, level: number, message: string, line: number, sourceId: string) => void	Called when the `console-message` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the context-menu event.

Signature:

once(event: "context-menu", listener: (event: ElectronEvent, params: ElectronContextMenuParams) => void): this

Parameters:

Parameter	Type	Description
event	"context-menu"	The event name.
listener	(event: ElectronEvent, params: ElectronContextMenuParams) => void	Called when the `context-menu` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the crashed event.

Signature:

once(event: "crashed", listener: (event: ElectronEvent, killed: boolean) => void): this

Parameters:

Parameter	Type	Description
event	"crashed"	The event name.
listener	(event: ElectronEvent, killed: boolean) => void	Called when the `crashed` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the cursor-changed event.

Signature:

once(event: "cursor-changed", listener: (event: ElectronEvent, type: string, image: ElectronNativeImage, scale: number, size: ElectronSize, hotspot: ElectronPoint) => void): this

Parameters:

Parameter	Type	Description
event	"cursor-changed"	The event name.
listener	(event: ElectronEvent, type: string, image: ElectronNativeImage, scale: number, size: ElectronSize, hotspot: ElectronPoint) => void	Called when the `cursor-changed` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the destroyed event.

Signature:

once(event: "destroyed", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"destroyed"	The event name.
listener	(...args: unknown[]) => void	Called when the `destroyed` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the devtools-closed event.

Signature:

once(event: "devtools-closed", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"devtools-closed"	The event name.
listener	(...args: unknown[]) => void	Called when the `devtools-closed` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the devtools-focused event.

Signature:

once(event: "devtools-focused", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"devtools-focused"	The event name.
listener	(...args: unknown[]) => void	Called when the `devtools-focused` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the devtools-opened event.

Signature:

once(event: "devtools-opened", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"devtools-opened"	The event name.
listener	(...args: unknown[]) => void	Called when the `devtools-opened` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the devtools-reload-page event.

Signature:

once(event: "devtools-reload-page", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"devtools-reload-page"	The event name.
listener	(...args: unknown[]) => void	Called when the `devtools-reload-page` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-attach-webview event.

Signature:

once(event: "did-attach-webview", listener: (event: ElectronEvent, webContents: ElectronWebContents) => void): this

Parameters:

Parameter	Type	Description
event	"did-attach-webview"	The event name.
listener	(event: ElectronEvent, webContents: ElectronWebContents) => void	Called when the `did-attach-webview` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-change-theme-color event.

Signature:

once(event: "did-change-theme-color", listener: (event: ElectronEvent, color: string | null) => void): this

Parameters:

Parameter	Type	Description
event	"did-change-theme-color"	The event name.
listener	(event: ElectronEvent, color: string \| null) => void	Called when the `did-change-theme-color` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-create-window event.

Signature:

once(event: "did-create-window", listener: (window: ElectronBrowserWindow, details: ElectronDidCreateWindowDetails) => void): this

Parameters:

Parameter	Type	Description
event	"did-create-window"	The event name.
listener	(window: ElectronBrowserWindow, details: ElectronDidCreateWindowDetails) => void	Called when the `did-create-window` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-fail-load event.

Signature:

once(event: "did-fail-load", listener: (event: ElectronEvent, errorCode: number, errorDescription: string, validatedURL: string, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void): this

Parameters:

Parameter	Type	Description
event	"did-fail-load"	The event name.
listener	(event: ElectronEvent, errorCode: number, errorDescription: string, validatedURL: string, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void	Called when the `did-fail-load` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-fail-provisional-load event.

Signature:

once(event: "did-fail-provisional-load", listener: (event: ElectronEvent, errorCode: number, errorDescription: string, validatedURL: string, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void): this

Parameters:

Parameter	Type	Description
event	"did-fail-provisional-load"	The event name.
listener	(event: ElectronEvent, errorCode: number, errorDescription: string, validatedURL: string, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void	Called when the `did-fail-provisional-load` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-finish-load event.

Signature:

once(event: "did-finish-load", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"did-finish-load"	The event name.
listener	(...args: unknown[]) => void	Called when the `did-finish-load` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-frame-finish-load event.

Signature:

once(event: "did-frame-finish-load", listener: (event: ElectronEvent, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void): this

Parameters:

Parameter	Type	Description
event	"did-frame-finish-load"	The event name.
listener	(event: ElectronEvent, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void	Called when the `did-frame-finish-load` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-frame-navigate event.

Signature:

once(event: "did-frame-navigate", listener: (event: ElectronEvent, url: string, httpResponseCode: number, httpStatusText: string, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void): this

Parameters:

Parameter	Type	Description
event	"did-frame-navigate"	The event name.
listener	(event: ElectronEvent, url: string, httpResponseCode: number, httpStatusText: string, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void	Called when the `did-frame-navigate` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-navigate event.

Signature:

once(event: "did-navigate", listener: (event: ElectronEvent, url: string, httpResponseCode: number, httpStatusText: string) => void): this

Parameters:

Parameter	Type	Description
event	"did-navigate"	The event name.
listener	(event: ElectronEvent, url: string, httpResponseCode: number, httpStatusText: string) => void	Called when the `did-navigate` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-navigate-in-page event.

Signature:

once(event: "did-navigate-in-page", listener: (event: ElectronEvent, url: string, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void): this

Parameters:

Parameter	Type	Description
event	"did-navigate-in-page"	The event name.
listener	(event: ElectronEvent, url: string, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void	Called when the `did-navigate-in-page` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-redirect-navigation event.

Signature:

once(event: "did-redirect-navigation", listener: (event: ElectronEvent, url: string, isInPlace: boolean, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void): this

Parameters:

Parameter	Type	Description
event	"did-redirect-navigation"	The event name.
listener	(event: ElectronEvent, url: string, isInPlace: boolean, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void	Called when the `did-redirect-navigation` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-start-loading event.

Signature:

once(event: "did-start-loading", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"did-start-loading"	The event name.
listener	(...args: unknown[]) => void	Called when the `did-start-loading` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-start-navigation event.

Signature:

once(event: "did-start-navigation", listener: (event: ElectronEvent, url: string, isInPlace: boolean, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void): this

Parameters:

Parameter	Type	Description
event	"did-start-navigation"	The event name.
listener	(event: ElectronEvent, url: string, isInPlace: boolean, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void	Called when the `did-start-navigation` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the did-stop-loading event.

Signature:

once(event: "did-stop-loading", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"did-stop-loading"	The event name.
listener	(...args: unknown[]) => void	Called when the `did-stop-loading` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the dom-ready event.

Signature:

once(event: "dom-ready", listener: (event: ElectronEvent) => void): this

Parameters:

Parameter	Type	Description
event	"dom-ready"	The event name.
listener	(event: ElectronEvent) => void	Called when the `dom-ready` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the enter-html-full-screen event.

Signature:

once(event: "enter-html-full-screen", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"enter-html-full-screen"	The event name.
listener	(...args: unknown[]) => void	Called when the `enter-html-full-screen` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the focus event.

Signature:

once(event: "focus", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"focus"	The event name.
listener	(...args: unknown[]) => void	Called when the `focus` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the found-in-page event.

Signature:

once(event: "found-in-page", listener: (event: ElectronEvent, result: ElectronResult) => void): this

Parameters:

Parameter	Type	Description
event	"found-in-page"	The event name.
listener	(event: ElectronEvent, result: ElectronResult) => void	Called when the `found-in-page` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the frame-created event.

Signature:

once(event: "frame-created", listener: (event: ElectronEvent, details: ElectronFrameCreatedDetails) => void): this

Parameters:

Parameter	Type	Description
event	"frame-created"	The event name.
listener	(event: ElectronEvent, details: ElectronFrameCreatedDetails) => void	Called when the `frame-created` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the ipc-message event.

Signature:

once(event: "ipc-message", listener: (event: ElectronEvent, channel: string, ...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"ipc-message"	The event name.
listener	(event: ElectronEvent, channel: string, ...args: unknown[]) => void	Called when the `ipc-message` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the ipc-message-sync event.

Signature:

once(event: "ipc-message-sync", listener: (event: ElectronEvent, channel: string, ...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"ipc-message-sync"	The event name.
listener	(event: ElectronEvent, channel: string, ...args: unknown[]) => void	Called when the `ipc-message-sync` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the leave-html-full-screen event.

Signature:

once(event: "leave-html-full-screen", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"leave-html-full-screen"	The event name.
listener	(...args: unknown[]) => void	Called when the `leave-html-full-screen` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the login event.

Signature:

once(event: "login", listener: (event: ElectronEvent, authenticationResponseDetails: ElectronAuthenticationResponseDetails, authInfo: ElectronAuthInfo, callback: (username?: string | undefined, password?: string | undefined) => void) => void): this

Parameters:

Parameter	Type	Description
event	"login"	The event name.
listener	(event: ElectronEvent, authenticationResponseDetails: ElectronAuthenticationResponseDetails, authInfo: ElectronAuthInfo, callback: (username?: string \| undefined, password?: string \| undefined) => void) => void	Called when the `login` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the media-paused event.

Signature:

once(event: "media-paused", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"media-paused"	The event name.
listener	(...args: unknown[]) => void	Called when the `media-paused` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the media-started-playing event.

Signature:

once(event: "media-started-playing", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"media-started-playing"	The event name.
listener	(...args: unknown[]) => void	Called when the `media-started-playing` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the new-window event.

Signature:

once(event: "new-window", listener: (event: ElectronNewWindowWebContentsEvent, url: string, frameName: string, disposition: "new-window" | "background-tab" | "default" | "foreground-tab" | "other" | "save-to-disk", options: BrowserWindowConstructorOptions, additionalFeatures: string[], referrer: ElectronReferrer, postBody: ElectronPostBody) => void): this

Parameters:

Parameter	Type	Description
event	"new-window"	The event name.
listener	(event: ElectronNewWindowWebContentsEvent, url: string, frameName: string, disposition: "new-window" \| "background-tab" \| "default" \| "foreground-tab" \| "other" \| "save-to-disk", options: BrowserWindowConstructorOptions, additionalFeatures: string[], referrer: ElectronReferrer, postBody: ElectronPostBody) => void	Called when the `new-window` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the page-favicon-updated event.

Signature:

once(event: "page-favicon-updated", listener: (event: ElectronEvent, favicons: string[]) => void): this

Parameters:

Parameter	Type	Description
event	"page-favicon-updated"	The event name.
listener	(event: ElectronEvent, favicons: string[]) => void	Called when the `page-favicon-updated` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the page-title-updated event.

Signature:

once(event: "page-title-updated", listener: (event: ElectronEvent, title: string, explicitSet: boolean) => void): this

Parameters:

Parameter	Type	Description
event	"page-title-updated"	The event name.
listener	(event: ElectronEvent, title: string, explicitSet: boolean) => void	Called when the `page-title-updated` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the paint event.

Signature:

once(event: "paint", listener: (event: ElectronEvent, dirtyRect: ElectronRectangle, image: ElectronNativeImage) => void): this

Parameters:

Parameter	Type	Description
event	"paint"	The event name.
listener	(event: ElectronEvent, dirtyRect: ElectronRectangle, image: ElectronNativeImage) => void	Called when the `paint` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the plugin-crashed event.

Signature:

once(event: "plugin-crashed", listener: (event: ElectronEvent, name: string, version: string) => void): this

Parameters:

Parameter	Type	Description
event	"plugin-crashed"	The event name.
listener	(event: ElectronEvent, name: string, version: string) => void	Called when the `plugin-crashed` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the preferred-size-changed event.

Signature:

once(event: "preferred-size-changed", listener: (event: ElectronEvent, preferredSize: ElectronSize) => void): this

Parameters:

Parameter	Type	Description
event	"preferred-size-changed"	The event name.
listener	(event: ElectronEvent, preferredSize: ElectronSize) => void	Called when the `preferred-size-changed` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the preload-error event.

Signature:

once(event: "preload-error", listener: (event: ElectronEvent, preloadPath: string, error: Error) => void): this

Parameters:

Parameter	Type	Description
event	"preload-error"	The event name.
listener	(event: ElectronEvent, preloadPath: string, error: Error) => void	Called when the `preload-error` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the render-process-gone event.

Signature:

once(event: "render-process-gone", listener: (event: ElectronEvent, details: ElectronRenderProcessGoneDetails) => void): this

Parameters:

Parameter	Type	Description
event	"render-process-gone"	The event name.
listener	(event: ElectronEvent, details: ElectronRenderProcessGoneDetails) => void	Called when the `render-process-gone` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the responsive event.

Signature:

once(event: "responsive", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"responsive"	The event name.
listener	(...args: unknown[]) => void	Called when the `responsive` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the select-bluetooth-device event.

Signature:

once(event: "select-bluetooth-device", listener: (event: ElectronEvent, devices: ElectronBluetoothDevice[], callback: (deviceId: string) => void) => void): this

Parameters:

Parameter	Type	Description
event	"select-bluetooth-device"	The event name.
listener	(event: ElectronEvent, devices: ElectronBluetoothDevice[], callback: (deviceId: string) => void) => void	Called when the `select-bluetooth-device` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the select-client-certificate event.

Signature:

once(event: "select-client-certificate", listener: (event: ElectronEvent, url: string, certificateList: ElectronCertificate[], callback: (certificate: ElectronCertificate) => void) => void): this

Parameters:

Parameter	Type	Description
event	"select-client-certificate"	The event name.
listener	(event: ElectronEvent, url: string, certificateList: ElectronCertificate[], callback: (certificate: ElectronCertificate) => void) => void	Called when the `select-client-certificate` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the unresponsive event.

Signature:

once(event: "unresponsive", listener: (...args: unknown[]) => void): this

Parameters:

Parameter	Type	Description
event	"unresponsive"	The event name.
listener	(...args: unknown[]) => void	Called when the `unresponsive` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the update-target-url event.

Signature:

once(event: "update-target-url", listener: (event: ElectronEvent, url: string) => void): this

Parameters:

Parameter	Type	Description
event	"update-target-url"	The event name.
listener	(event: ElectronEvent, url: string) => void	Called when the `update-target-url` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the will-attach-webview event.

Signature:

once(event: "will-attach-webview", listener: (event: ElectronEvent, webPreferences: WebPreferences, params: Record<string, string>) => void): this

Parameters:

Parameter	Type	Description
event	"will-attach-webview"	The event name.
listener	(event: ElectronEvent, webPreferences: WebPreferences, params: Record<string, string>) => void	Called when the `will-attach-webview` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the will-navigate event.

Signature:

once(event: "will-navigate", listener: (event: ElectronEvent, url: string) => void): this

Parameters:

Parameter	Type	Description
event	"will-navigate"	The event name.
listener	(event: ElectronEvent, url: string) => void	Called when the `will-navigate` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the will-prevent-unload event.

Signature:

once(event: "will-prevent-unload", listener: (event: ElectronEvent) => void): this

Parameters:

Parameter	Type	Description
event	"will-prevent-unload"	The event name.
listener	(event: ElectronEvent) => void	Called when the `will-prevent-unload` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the will-redirect event.

Signature:

once(event: "will-redirect", listener: (event: ElectronEvent, url: string, isInPlace: boolean, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void): this

Parameters:

Parameter	Type	Description
event	"will-redirect"	The event name.
listener	(event: ElectronEvent, url: string, isInPlace: boolean, isMainFrame: boolean, frameProcessId: number, frameRoutingId: number) => void	Called when the `will-redirect` event is emitted.

Returns: this — This web contents instance.

Unofficial

Registers a one-time listener for the zoom-changed event.

Signature:

once(event: "zoom-changed", listener: (event: ElectronEvent, zoomDirection: "in" | "out") => void): this

Parameters:

Parameter	Type	Description
event	"zoom-changed"	The event name.
listener	(event: ElectronEvent, zoomDirection: "in" \| "out") => void	Called when the `zoom-changed` event is emitted.

Returns: this — This web contents instance.