Interface FileReader

    Lets web applications asynchronously read the contents of files (or raw data buffers) stored on the user's computer, using File or Blob objects to specify the file or data to read.

    MDN Reference

    interface FileReader {
        DONE: 2;
        EMPTY: 0;
        error: DOMException;
        LOADING: 1;
        onabort: ((this: FileReader, ev: ProgressEvent<FileReader>) => any);
        onerror: ((this: FileReader, ev: ProgressEvent<FileReader>) => any);
        onload: ((this: FileReader, ev: ProgressEvent<FileReader>) => any);
        onloadend: ((this: FileReader, ev: ProgressEvent<FileReader>) => any);
        onloadstart: ((this: FileReader, ev: ProgressEvent<FileReader>) => any);
        onprogress: ((this: FileReader, ev: ProgressEvent<FileReader>) => any);
        readyState: 0 | 1 | 2;
        result: string | ArrayBuffer;
        abort(): void;
        addEventListener<K>(type: K, listener: ((this: FileReader, ev: FileReaderEventMap[K]) => any), options?: boolean | AddEventListenerOptions): void;
        addEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | AddEventListenerOptions): void;
        dispatchEvent(event: Event): boolean;
        readAsArrayBuffer(blob: Blob): void;
        readAsBinaryString(blob: Blob): void;
        readAsDataURL(blob: Blob): void;
        readAsText(blob: Blob, encoding?: string): void;
        removeEventListener<K>(type: K, listener: ((this: FileReader, ev: FileReaderEventMap[K]) => any), options?: boolean | EventListenerOptions): void;
        removeEventListener(type: string, listener: EventListenerOrEventListenerObject, options?: boolean | EventListenerOptions): void;
    }
    Hierarchy

    Properties

    DONE EMPTY error LOADING onabort onerror onload onloadend onloadstart onprogress readyState result

    Methods

    abort addEventListener dispatchEvent readAsArrayBuffer readAsBinaryString readAsDataURL readAsText removeEventListener

    Properties

    ReadonlyDONE

    DONE: 2

    ReadonlyEMPTY

    EMPTY: 0

    Readonlyerror

    error: DOMException

    MDN Reference

    ReadonlyLOADING

    LOADING: 1

    onabort

    onabort: ((this: FileReader, ev: ProgressEvent<FileReader>) => any)

    MDN Reference

    onerror

    onerror: ((this: FileReader, ev: ProgressEvent<FileReader>) => any)

    MDN Reference

    onload

    onload: ((this: FileReader, ev: ProgressEvent<FileReader>) => any)

    MDN Reference

    onloadend

    onloadend: ((this: FileReader, ev: ProgressEvent<FileReader>) => any)

    MDN Reference

    onloadstart

    onloadstart: ((this: FileReader, ev: ProgressEvent<FileReader>) => any)

    MDN Reference

    onprogress

    onprogress: ((this: FileReader, ev: ProgressEvent<FileReader>) => any)

    MDN Reference

    ReadonlyreadyState

    readyState: 0 | 1 | 2

    MDN Reference

    Readonlyresult

    result: string | ArrayBuffer

    MDN Reference

    Methods

    abort

    addEventListener

    • addEventListener<K>(type, listener, options?): void

    • Appends an event listener for events whose type attribute value is type. The callback argument sets the callback that will be invoked when the event is dispatched.

      The options argument sets listener-specific options. For compatibility this can be a boolean, in which case the method behaves exactly as if the value was specified as options's capture.

      When set to true, options's capture prevents callback from being invoked when the event's eventPhase attribute value is BUBBLING_PHASE. When false (or not present), callback will not be invoked when event's eventPhase attribute value is CAPTURING_PHASE. Either way, callback will be invoked if event's eventPhase attribute value is AT_TARGET.

      When set to true, options's passive indicates that the callback will not cancel the event by invoking preventDefault(). This is used to enable performance optimizations described in § 2.8 Observing event listeners.

      When set to true, options's once indicates that the callback will only be invoked once after which the event listener will be removed.

      If an AbortSignal is passed for options's signal, then the event listener will be removed when signal is aborted.

      The event listener is appended to target's event listener list and is not appended if it has the same type, callback, and capture.

      MDN Reference

      Type Parameters

      Parameters

      Returns void

    • addEventListener(type, listener, options?): void

    • Appends an event listener for events whose type attribute value is type. The callback argument sets the callback that will be invoked when the event is dispatched.

      The options argument sets listener-specific options. For compatibility this can be a boolean, in which case the method behaves exactly as if the value was specified as options's capture.

      When set to true, options's capture prevents callback from being invoked when the event's eventPhase attribute value is BUBBLING_PHASE. When false (or not present), callback will not be invoked when event's eventPhase attribute value is CAPTURING_PHASE. Either way, callback will be invoked if event's eventPhase attribute value is AT_TARGET.

      When set to true, options's passive indicates that the callback will not cancel the event by invoking preventDefault(). This is used to enable performance optimizations described in § 2.8 Observing event listeners.

      When set to true, options's once indicates that the callback will only be invoked once after which the event listener will be removed.

      If an AbortSignal is passed for options's signal, then the event listener will be removed when signal is aborted.

      The event listener is appended to target's event listener list and is not appended if it has the same type, callback, and capture.

      MDN Reference

      Parameters

      Returns void

    dispatchEvent

    • dispatchEvent(event): boolean

    • Dispatches a synthetic event event to target and returns true if either event's cancelable attribute value is false or its preventDefault() method was not invoked, and false otherwise.

      MDN Reference

      Parameters

      Returns boolean

    readAsArrayBuffer

    readAsBinaryString

    • readAsBinaryString(blob): void

    • Parameters

      Returns void

      Deprecated

      MDN Reference

    readAsDataURL

    readAsText

    • readAsText(blob, encoding?): void

    • MDN Reference

      Parameters

      • blob: Blob
      • Optionalencoding: string

      Returns void

    removeEventListener

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