New: Initial attempt on a backwards compatible fetch implementation w…

…ith binary support, see protocolbuffers#661

lib/fetch/index.js

@@ -15,38 +15,99 @@ var fs = inquire("fs");
  * @returns {undefined}
  */
 
+/**
+ * Options as used by {@link util.fetch}.
+ * @typedef {Object}
+ * @property {boolean} [binary=false] Whether expecting a binary response or not
+ */
+
 /**
  * Fetches the contents of a file.
  * @memberof util
- * @param {string} path File path or url
- * @param {FetchCallback} [callback] Callback function
- * @returns {Promise<string>} A Promise if `callback` has been omitted, otherwise `undefined`
- * @property {function(string, FetchCallback=):Promise<string>} xhr XHR/browser fetch with an identical signature
+ * @param {string} filename File path or url
+ * @param {FetchOptions} options Fetch options
+ * @param {FetchCallback} callback Callback function
+ * @returns {undefined}
  */
-function fetch(path, callback) {
+function fetch(filename, options, callback) {
+    if (typeof options === "function") {
+        callback = options;
+        options = {};
+    } else if (!options)
+        options = {};
+
     if (!callback)
-        return asPromise(fetch, this, path); // eslint-disable-line no-invalid-this
+        return asPromise(fetch, this, filename, options); // eslint-disable-line no-invalid-this
+
+    // if a node-like filesystem is present, try it first but fall back to XHR if nothing is found.
     if (fs && fs.readFile)
-        return fs.readFile(path, "utf8", function fetchReadFileCallback(err, contents) {
+        return fs.readFile(filename, function fetchReadFileCallback(err, contents) {
             return err && typeof XMLHttpRequest !== "undefined"
-                ? fetch.xhr(path, callback)
-                : callback(err, contents);
+                ? fetch.xhr(filename, options, callback)
+                : err
+                ? callback(err)
+                : callback(null, options.binary ? contents : contents.toString("utf8"));
         });
-    return fetch.xhr(path, callback);
+
+    // use the XHR version otherwise.
+    return fetch.xhr(filename, options, callback);
 }
 
-fetch.xhr = function fetch_xhr(path, callback) {
+/**
+ * Fetches the contents of a file.
+ * @name util.fetch
+ * @function
+ * @param {string} path File path or url
+ * @param {FetchCallback} callback Callback function
+ * @returns {undefined}
+ * @variation 2
+ */
+
+/**
+ * Fetches the contents of a file.
+ * @name util.fetch
+ * @function
+ * @param {string} path File path or url
+ * @param {FetchOptions} [options] Fetch options
+ * @returns {Promise<string|Uint8Array>} Promise
+ * @variation 3
+ */
+
+/**/
+fetch.xhr = function fetch_xhr(filename, options, callback) {
     var xhr = new XMLHttpRequest();
     xhr.onreadystatechange /* works everywhere */ = function fetchOnReadyStateChange() {
-        return xhr.readyState === 4
-            ? xhr.status === 0 || xhr.status === 200
-            ? callback(null, xhr.responseText)
-            : callback(Error("status " + xhr.status))
-            : undefined;
+
+        if (xhr.readyState !== 4)
+            return undefined;
+
         // local cors security errors return status 0 / empty string, too. afaik this cannot be
         // reliably distinguished from an actually empty file for security reasons. feel free
         // to send a pull request if you are aware of a solution.
+        if (xhr.status !== 0 && xhr.status !== 200)
+            return callback(Error("status " + xhr.status));
+
+        // if binary data is expected, make sure that some sort of array is returned, even if
+        // ArrayBuffers are not supported. the binary string fallback, however, is unsafe.
+        if (options.binary) {
+            var buffer = xhr.response;
+            if (!buffer) {
+                buffer = [];
+                for (var i = 0; i < xhr.responseText.length; ++i)
+                    buffer.push(xhr.responseText.charCodeAt(i) & 255);
+            }
+            return callback(null, typeof Uint8Array !== "undefined" ? new Uint8Array(buffer) : buffer);
+        }
+        return callback(null, xhr.responseText);
     };
-    xhr.open("GET", path);
+
+    if (options.binary) {
+        // ref: https://developer.mozilla.org/en-US/docs/Web/API/XMLHttpRequest/Sending_and_Receiving_Binary_Data#Receiving_binary_data_in_older_browsers
+        if ("overrideMimeType" in xhr)
+            xhr.overrideMimeType("text/plain; charset=x-user-defined");
+        xhr.responseType = "arraybuffer";
+    }
+
+    xhr.open("GET", filename);
     xhr.send();
 };

lib/fetch/package.json

@@ -1,7 +1,7 @@
 {
   "name": "@protobufjs/fetch",
   "description": "Fetches the contents of a file accross node and browsers.",
-  "version": "1.0.4",
+  "version": "1.0.5",
   "author": "Daniel Wirtz <dcode+protobufjs@dcode.io>",
   "repository": {
     "type": "git",

lib/fetch/tests/index.js

@@ -10,7 +10,7 @@ tape.test("fetch", function(test) {
         test.ok(promise instanceof Promise, "should return a promise if callback has been omitted");
     }
 
-    // TODO
+    // TODO - some what to test this properly?
 
     test.end();
 });

scripts/bundle.js

@@ -13,6 +13,8 @@ var buffer     = require("vinyl-buffer");
 var vinylfs    = require("vinyl-fs");
 var source     = require("vinyl-source-stream");
 
+var zopfli     = require("node-zopfli");
+
 var pkg = require(__dirname + "/../package.json");
 
 var license = [
@@ -86,9 +88,6 @@ function bundle(options) {
     .on("error", gutil.log);
 }
 
-var fs     = require("fs");
-var zopfli = require("node-zopfli");
-
 /**
  * Compresses a file using zopfli gzip.
  * @param {string} sourceFile Source file

tests/node/lib_fetch.js

@@ -0,0 +1 @@
+require("../../lib/fetch/tests");