Added babel transpiler of core library down to es2015 syntax.

gulpfile.js

@@ -26,6 +26,7 @@ var bump        = require('gulp-bump');
 var wrapUmd     = require("gulp-wrap-umd");
 var awspublish  = require('gulp-awspublish');
 var gulpTemplate = require('gulp-template');
+var babel       = require('gulp-babel');
 
 // custom builder_helper stripper to remove builder helper functions
 var stripper = require("./gulp/gulp-stripper");
@@ -38,11 +39,15 @@ var VERSIONABLE_FILES = [
 
 var paths = {
     scripts: {
+        filesToTranspile:[
+            "src/js/Alpaca-async.js",
+        ],
         core: [
+            "src/js/polyfills/*.js",
             "thirdparty/base/Base.js",
 
             "src/js/Alpaca.js",
-            "src/js/Alpaca-async.js",
+            "build/tmp/transpiled/Alpaca-async.js",
             "src/js/ObservableUtils.js",
             "src/js/Observables.js",
             "src/js/Observable.js",
@@ -399,13 +404,26 @@ gulp.task("build-scripts", function(cb) {
 
     //console.log("build-scripts start");
     // core
-    var first = gulp.src(paths.scripts.core)
-                    .pipe(concat('scripts-core.js'))
-                    .pipe(gulp.dest('build/tmp'));
-
-    first.on("end", function() {
-
-        es.concat(
+    var first = gulp.src(paths.scripts.filesToTranspile)
+                    .pipe(babel({
+                        presets: [
+                            ['@babel/preset-env', {
+                                targets: {
+                                    'ie': '9'
+                                }
+                            }]
+                        ]
+                    }))                                            
+                    .pipe(gulp.dest('build/tmp/transpiled'));
+
+    first.on("end", function(){
+        var second = gulp.src(paths.scripts.core)                                 
+                        .pipe(concat('scripts-core.js'))                                            
+                        .pipe(gulp.dest('build/tmp'));
+
+        second.on("end", function() {
+
+            es.concat(
 
             // web
             gulp.src(paths.scripts.web)
@@ -443,13 +461,14 @@ gulp.task("build-scripts", function(cb) {
                 .pipe(uglify())
                 .pipe(gulp.dest('build/alpaca/jquerymobile'))
 
-        ).pipe(es.wait(function() {
+            ).pipe(es.wait(function() {
 
             //console.log("build-scripts completed");
             cb();
 
-        })).pipe(notify({message: "Built Alpaca JS"}));
-    });
+            })).pipe(notify({message: "Built Alpaca JS"}));
+        });
+    })
 });
 
 gulp.task("build-styles", function(cb) {

package.json

@@ -15,6 +15,8 @@
   "version": "1.5.27",
   "main": "dist/alpaca/bootstrap/alpaca.js",
   "devDependencies": {
+    "@babel/core": "^7.4.5",
+    "@babel/preset-env": "^7.4.5",
     "bower": "^1.8.8",
     "cucumber": "~0.3.3",
     "event-stream": "^4.0.1",
@@ -26,6 +28,7 @@
     "grunt-jsdoc": "^2.3.0",
     "gulp": "^3.9.1",
     "gulp-awspublish": "^3.4.0",
+    "gulp-babel": "^8.0.0",
     "gulp-bump": "^3.1.1",
     "gulp-clean": "^0.4.0",
     "gulp-concat": "^2.6.1",

src/js/polyfills/ArrayFromPolyfill.js

@@ -0,0 +1,79 @@
+// This polyfill is taken from MDN: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from#Polyfill
+// Production steps of ECMA-262, Edition 6, 22.1.2.1
+if (!Array.from) {
+	Array.from = (function () {
+	  var toStr = Object.prototype.toString;
+	  var isCallable = function (fn) {
+		return typeof fn === 'function' || toStr.call(fn) === '[object Function]';
+	  };
+	  var toInteger = function (value) {
+		var number = Number(value);
+		if (isNaN(number)) { return 0; }
+		if (number === 0 || !isFinite(number)) { return number; }
+		return (number > 0 ? 1 : -1) * Math.floor(Math.abs(number));
+	  };
+	  var maxSafeInteger = Math.pow(2, 53) - 1;
+	  var toLength = function (value) {
+		var len = toInteger(value);
+		return Math.min(Math.max(len, 0), maxSafeInteger);
+	  };
+
+	  // The length property of the from method is 1.
+	  return function from(arrayLike/*, mapFn, thisArg */) {
+		// 1. Let C be the this value.
+		var C = this;
+
+		// 2. Let items be ToObject(arrayLike).
+		var items = Object(arrayLike);
+
+		// 3. ReturnIfAbrupt(items).
+		if (arrayLike == null) {
+		  throw new TypeError('Array.from requires an array-like object - not null or undefined');
+		}
+
+		// 4. If mapfn is undefined, then let mapping be false.
+		var mapFn = arguments.length > 1 ? arguments[1] : void undefined;
+		var T;
+		if (typeof mapFn !== 'undefined') {
+		  // 5. else
+		  // 5. a If IsCallable(mapfn) is false, throw a TypeError exception.
+		  if (!isCallable(mapFn)) {
+			throw new TypeError('Array.from: when provided, the second argument must be a function');
+		  }
+
+		  // 5. b. If thisArg was supplied, let T be thisArg; else let T be undefined.
+		  if (arguments.length > 2) {
+			T = arguments[2];
+		  }
+		}
+
+		// 10. Let lenValue be Get(items, "length").
+		// 11. Let len be ToLength(lenValue).
+		var len = toLength(items.length);
+
+		// 13. If IsConstructor(C) is true, then
+		// 13. a. Let A be the result of calling the [[Construct]] internal method 
+		// of C with an argument list containing the single item len.
+		// 14. a. Else, Let A be ArrayCreate(len).
+		var A = isCallable(C) ? Object(new C(len)) : new Array(len);
+
+		// 16. Let k be 0.
+		var k = 0;
+		// 17. Repeat, while k < len… (also steps a - h)
+		var kValue;
+		while (k < len) {
+		  kValue = items[k];
+		  if (mapFn) {
+			A[k] = typeof T === 'undefined' ? mapFn(kValue, k) : mapFn.call(T, kValue, k);
+		  } else {
+			A[k] = kValue;
+		  }
+		  k += 1;
+		}
+		// 18. Let putStatus be Put(A, "length", len, true).
+		A.length = len;
+		// 20. Return A.
+		return A;
+	  };
+	}());
+  }