mirror of
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116 lines
3.8 KiB
JavaScript
116 lines
3.8 KiB
JavaScript
"use strict";
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module.exports = fetch;
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var asPromise = require("@protobufjs/aspromise"),
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inquire = require("@protobufjs/inquire");
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var fs = inquire("fs");
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/**
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* Node-style callback as used by {@link util.fetch}.
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* @typedef FetchCallback
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* @type {function}
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* @param {?Error} error Error, if any, otherwise `null`
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* @param {string} [contents] File contents, if there hasn't been an error
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* @returns {undefined}
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*/
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/**
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* Options as used by {@link util.fetch}.
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* @typedef FetchOptions
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* @type {Object}
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* @property {boolean} [binary=false] Whether expecting a binary response
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* @property {boolean} [xhr=false] If `true`, forces the use of XMLHttpRequest
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*/
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/**
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* Fetches the contents of a file.
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* @memberof util
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* @param {string} filename File path or url
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* @param {FetchOptions} options Fetch options
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* @param {FetchCallback} callback Callback function
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* @returns {undefined}
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*/
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function fetch(filename, options, callback) {
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if (typeof options === "function") {
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callback = options;
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options = {};
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} else if (!options)
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options = {};
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if (!callback)
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return asPromise(fetch, this, filename, options); // eslint-disable-line no-invalid-this
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// if a node-like filesystem is present, try it first but fall back to XHR if nothing is found.
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if (!options.xhr && fs && fs.readFile)
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return fs.readFile(filename, function fetchReadFileCallback(err, contents) {
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return err && typeof XMLHttpRequest !== "undefined"
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? fetch.xhr(filename, options, callback)
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: err
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? callback(err)
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: callback(null, options.binary ? contents : contents.toString("utf8"));
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});
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// use the XHR version otherwise.
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return fetch.xhr(filename, options, callback);
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}
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/**
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* Fetches the contents of a file.
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* @name util.fetch
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* @function
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* @param {string} path File path or url
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* @param {FetchCallback} callback Callback function
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* @returns {undefined}
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* @variation 2
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*/
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/**
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* Fetches the contents of a file.
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* @name util.fetch
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* @function
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* @param {string} path File path or url
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* @param {FetchOptions} [options] Fetch options
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* @returns {Promise<string|Uint8Array>} Promise
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* @variation 3
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*/
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/**/
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fetch.xhr = function fetch_xhr(filename, options, callback) {
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var xhr = new XMLHttpRequest();
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xhr.onreadystatechange /* works everywhere */ = function fetchOnReadyStateChange() {
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if (xhr.readyState !== 4)
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return undefined;
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// local cors security errors return status 0 / empty string, too. afaik this cannot be
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// reliably distinguished from an actually empty file for security reasons. feel free
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// to send a pull request if you are aware of a solution.
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if (xhr.status !== 0 && xhr.status !== 200)
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return callback(Error("status " + xhr.status));
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// if binary data is expected, make sure that some sort of array is returned, even if
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// ArrayBuffers are not supported. the binary string fallback, however, is unsafe.
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if (options.binary) {
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var buffer = xhr.response;
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if (!buffer) {
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buffer = [];
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for (var i = 0; i < xhr.responseText.length; ++i)
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buffer.push(xhr.responseText.charCodeAt(i) & 255);
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}
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return callback(null, typeof Uint8Array !== "undefined" ? new Uint8Array(buffer) : buffer);
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}
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return callback(null, xhr.responseText);
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};
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if (options.binary) {
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// ref: https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Sending_and_Receiving_Binary_Data#Receiving_binary_data_in_older_browsers
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if ("overrideMimeType" in xhr)
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xhr.overrideMimeType("text/plain; charset=x-user-defined");
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xhr.responseType = "arraybuffer";
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}
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xhr.open("GET", filename);
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xhr.send();
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};
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