mirror of https://github.com/denoland/deno.git
261 lines
8.7 KiB
JavaScript
261 lines
8.7 KiB
JavaScript
// Copyright 2018-2021 the Deno authors. All rights reserved. MIT license.
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((window) => {
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const base64 = window.__bootstrap.base64;
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async function readOperation(fr, blob, readtype) {
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// Implementation from https://w3c.github.io/FileAPI/ notes
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// And body of deno blob.ts readBytes
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fr.aborting = false;
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// 1. If fr’s state is "loading", throw an InvalidStateError DOMException.
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if (fr.readyState === FileReader.LOADING) {
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throw new DOMException(
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"Invalid FileReader state.",
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"InvalidStateError",
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);
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}
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// 2. Set fr’s state to "loading".
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fr.readyState = FileReader.LOADING;
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// 3. Set fr’s result to null.
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fr.result = null;
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// 4. Set fr’s error to null.
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fr.error = null;
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// 5. Let stream be the result of calling get stream on blob.
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const stream /*: ReadableStream<ArrayBufferView>*/ = blob.stream();
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// 6. Let reader be the result of getting a reader from stream.
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const reader = stream.getReader();
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// 7. Let bytes be an empty byte sequence.
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//let bytes = new Uint8Array();
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const chunks /*: Uint8Array[]*/ = [];
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// 8. Let chunkPromise be the result of reading a chunk from stream with reader.
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let chunkPromise = reader.read();
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// 9. Let isFirstChunk be true.
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let isFirstChunk = true;
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// 10 in parallel while true
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while (!fr.aborting) {
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// 1. Wait for chunkPromise to be fulfilled or rejected.
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try {
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const chunk = await chunkPromise;
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// 2. If chunkPromise is fulfilled, and isFirstChunk is true, queue a task to fire a progress event called loadstart at fr.
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if (isFirstChunk) {
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queueMicrotask(() => {
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// fire a progress event for loadstart
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const ev = new ProgressEvent("loadstart", {});
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fr.dispatchEvent(ev);
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});
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}
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// 3. Set isFirstChunk to false.
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isFirstChunk = false;
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// 4. If chunkPromise is fulfilled with an object whose done property is false
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// and whose value property is a Uint8Array object, run these steps:
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if (!chunk.done && chunk.value instanceof Uint8Array) {
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chunks.push(chunk.value);
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// TODO(bartlomieju): (only) If roughly 50ms have passed since last progress
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{
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const size = chunks.reduce((p, i) => p + i.byteLength, 0);
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const ev = new ProgressEvent("progress", {
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loaded: size,
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});
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fr.dispatchEvent(ev);
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}
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chunkPromise = reader.read();
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} // 5 Otherwise, if chunkPromise is fulfilled with an object whose done property is true, queue a task to run the following steps and abort this algorithm:
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else if (chunk.done === true) {
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queueMicrotask(() => {
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if (fr.aborting) {
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return;
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}
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// 1. Set fr’s state to "done".
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fr.readyState = FileReader.DONE;
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// 2. Let result be the result of package data given bytes, type, blob’s type, and encodingName.
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const size = chunks.reduce((p, i) => p + i.byteLength, 0);
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const bytes = new Uint8Array(size);
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let offs = 0;
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for (const chunk of chunks) {
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bytes.set(chunk, offs);
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offs += chunk.byteLength;
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}
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switch (readtype.kind) {
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case "ArrayBuffer": {
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fr.result = bytes.buffer;
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break;
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}
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case "Text": {
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const decoder = new TextDecoder(readtype.encoding);
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fr.result = decoder.decode(bytes.buffer);
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break;
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}
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case "DataUrl": {
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fr.result = "data:application/octet-stream;base64," +
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base64.fromByteArray(bytes);
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break;
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}
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}
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// 4.2 Fire a progress event called load at the fr.
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{
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const ev = new ProgressEvent("load", {
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lengthComputable: true,
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loaded: size,
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total: size,
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});
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fr.dispatchEvent(ev);
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}
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// 5. If fr’s state is not "loading", fire a progress event called loadend at the fr.
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//Note: Event handler for the load or error events could have started another load, if that happens the loadend event for this load is not fired.
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if (fr.readyState !== FileReader.LOADING) {
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const ev = new ProgressEvent("loadend", {
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lengthComputable: true,
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loaded: size,
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total: size,
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});
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fr.dispatchEvent(ev);
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}
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});
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break;
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}
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} catch (err) {
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if (fr.aborting) {
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break;
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}
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// chunkPromise rejected
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fr.readyState = FileReader.DONE;
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fr.error = err;
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{
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const ev = new ProgressEvent("error", {});
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fr.dispatchEvent(ev);
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}
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//If fr’s state is not "loading", fire a progress event called loadend at fr.
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//Note: Event handler for the error event could have started another load, if that happens the loadend event for this load is not fired.
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if (fr.readyState !== FileReader.LOADING) {
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const ev = new ProgressEvent("loadend", {});
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fr.dispatchEvent(ev);
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}
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break;
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}
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}
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}
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class FileReader extends EventTarget {
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error = null;
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readyState = FileReader.EMPTY;
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result = null;
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aborting = false;
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constructor() {
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super();
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}
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abort() {
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// If context object's state is "empty" or if context object's state is "done" set context object's result to null and terminate this algorithm.
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if (
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this.readyState === FileReader.EMPTY ||
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this.readyState === FileReader.DONE
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) {
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this.result = null;
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return;
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}
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// If context object's state is "loading" set context object's state to "done" and set context object's result to null.
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if (this.readyState === FileReader.LOADING) {
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this.readyState = FileReader.DONE;
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this.result = null;
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}
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// If there are any tasks from the context object on the file reading task source in an affiliated task queue, then remove those tasks from that task queue.
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// Terminate the algorithm for the read method being processed.
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this.aborting = true;
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// Fire a progress event called abort at the context object.
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const ev = new ProgressEvent("abort", {});
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this.dispatchEvent(ev);
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// If context object's state is not "loading", fire a progress event called loadend at the context object.
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if (this.readyState !== FileReader.LOADING) {
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const ev = new ProgressEvent("loadend", {});
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this.dispatchEvent(ev);
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}
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}
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readAsArrayBuffer(blob) {
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readOperation(this, blob, { kind: "ArrayBuffer" });
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}
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readAsBinaryString(blob) {
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// alias for readAsArrayBuffer
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readOperation(this, blob, { kind: "ArrayBuffer" });
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}
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readAsDataURL(blob) {
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readOperation(this, blob, { kind: "DataUrl" });
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}
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readAsText(blob, encoding) {
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readOperation(this, blob, { kind: "Text", encoding });
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}
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}
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FileReader.EMPTY = 0;
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FileReader.LOADING = 1;
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FileReader.DONE = 2;
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const handlerSymbol = Symbol("eventHandlers");
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function makeWrappedHandler(handler) {
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function wrappedHandler(...args) {
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if (typeof wrappedHandler.handler !== "function") {
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return;
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}
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return wrappedHandler.handler.call(this, ...args);
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}
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wrappedHandler.handler = handler;
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return wrappedHandler;
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}
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// TODO(benjamingr) reuse when we can reuse code between web crates
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function defineEventHandler(emitter, name) {
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// HTML specification section 8.1.5.1
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Object.defineProperty(emitter, `on${name}`, {
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get() {
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return this[handlerSymbol]?.get(name)?.handler;
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},
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set(value) {
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if (!this[handlerSymbol]) {
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this[handlerSymbol] = new Map();
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}
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let handlerWrapper = this[handlerSymbol]?.get(name);
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if (handlerWrapper) {
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handlerWrapper.handler = value;
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} else {
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handlerWrapper = makeWrappedHandler(value);
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this.addEventListener(name, handlerWrapper);
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}
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this[handlerSymbol].set(name, handlerWrapper);
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},
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configurable: true,
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enumerable: true,
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});
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}
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defineEventHandler(FileReader.prototype, "error");
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defineEventHandler(FileReader.prototype, "loadstart");
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defineEventHandler(FileReader.prototype, "load");
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defineEventHandler(FileReader.prototype, "loadend");
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defineEventHandler(FileReader.prototype, "progress");
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defineEventHandler(FileReader.prototype, "abort");
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window.__bootstrap.fileReader = {
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FileReader,
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};
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})(this);
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