FileReader-impl.js
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"use strict";
const whatwgEncoding = require("whatwg-encoding");
const MIMEType = require("whatwg-mimetype");
const querystring = require("querystring");
const DOMException = require("domexception");
const EventTargetImpl = require("../events/EventTarget-impl").implementation;
const ProgressEvent = require("../generated/ProgressEvent");
const { setupForSimpleEventAccessors } = require("../helpers/create-event-accessor");
const READY_STATES = Object.freeze({
EMPTY: 0,
LOADING: 1,
DONE: 2
});
const events = ["loadstart", "progress", "load", "abort", "error", "loadend"];
class FileReaderImpl extends EventTargetImpl {
constructor(args, privateData) {
super([], privateData);
this.error = null;
this.readyState = READY_STATES.EMPTY;
this.result = null;
this._ownerDocument = privateData.window.document;
this._terminated = false;
}
readAsArrayBuffer(file) {
this._readFile(file, "buffer");
}
readAsBinaryString(file) {
this._readFile(file, "binaryString");
}
readAsDataURL(file) {
this._readFile(file, "dataURL");
}
readAsText(file, encoding) {
this._readFile(file, "text", whatwgEncoding.labelToName(encoding) || "UTF-8");
}
abort() {
if (this.readyState === READY_STATES.EMPTY || this.readyState === READY_STATES.DONE) {
this.result = null;
return;
}
if (this.readyState === READY_STATES.LOADING) {
this.readyState = READY_STATES.DONE;
this.result = null;
}
this._terminated = true;
this._fireProgressEvent("abort");
this._fireProgressEvent("loadend");
}
_fireProgressEvent(name, props) {
const event = ProgressEvent.createImpl([name, Object.assign({ bubbles: false, cancelable: false }, props)], {});
this.dispatchEvent(event);
}
_readFile(file, format, encoding) {
if (this.readyState === READY_STATES.LOADING) {
throw new DOMException("The object is in an invalid state.", "InvalidStateError");
}
this.readyState = READY_STATES.LOADING;
setImmediate(() => {
if (this._terminated) {
this._terminated = false;
return;
}
this._fireProgressEvent("loadstart");
let data = file._buffer;
if (!data) {
data = Buffer.alloc(0);
}
this._fireProgressEvent("progress", {
lengthComputable: !isNaN(file.size),
total: file.size,
loaded: data.length
});
setImmediate(() => {
if (this._terminated) {
this._terminated = false;
return;
}
switch (format) {
default:
case "buffer": {
this.result = (new Uint8Array(data)).buffer;
break;
}
case "binaryString": {
this.result = data.toString("binary");
break;
}
case "dataURL": {
// Spec seems very unclear here; see https://github.com/whatwg/fetch/issues/665#issuecomment-362930079.
let dataUrl = "data:";
const contentType = MIMEType.parse(file.type);
if (contentType && contentType.type === "text") {
const fallbackEncoding = whatwgEncoding.getBOMEncoding(data) ||
whatwgEncoding.labelToName(contentType.parameters.get("charset")) || "UTF-8";
const decoded = whatwgEncoding.decode(data, fallbackEncoding);
contentType.parameters.set("charset", encoding);
dataUrl += contentType.toString();
dataUrl += ",";
dataUrl += querystring.escape(decoded);
} else {
if (contentType) {
dataUrl += contentType.toString();
}
dataUrl += ";base64,";
dataUrl += data.toString("base64");
}
this.result = dataUrl;
break;
}
case "text": {
this.result = whatwgEncoding.decode(data, encoding);
break;
}
}
this.readyState = READY_STATES.DONE;
this._fireProgressEvent("load");
this._fireProgressEvent("loadend");
});
});
}
}
setupForSimpleEventAccessors(FileReaderImpl.prototype, events);
exports.implementation = FileReaderImpl;