add toConsumableArray helper for spread - fixes #757

lib/6to5/transformation/file.js

@@ -41,6 +41,7 @@ File.helpers = [
   "tagged-template-literal-loose",
   "interop-require",
   "to-array",
+  "to-consumable-array",
   "sliced-to-array",
   "object-without-properties",
   "has-own",
@@ -216,19 +217,21 @@ File.prototype.debug = function (msg) {
   util.debug(parts);
 };
 
-File.prototype.toArray = function (node, i) {
+File.prototype.toArray = function (node, i, forceHelperName) {
   if (t.isArrayExpression(node)) {
     return node;
   } else if (t.isIdentifier(node) && node.name === "arguments") {
     return t.callExpression(t.memberExpression(this.addHelper("slice"), t.identifier("call")), [node]);
   } else {
-    var declarationName = "to-array";
+    var helperName = "to-array";
     var args = [node];
-    if (i) {
+    if (i === true) {
+      helperName = "to-consumable-array";
+    } else if (i) {
       args.push(t.literal(i));
-      declarationName = "sliced-to-array";
+      helperName = "sliced-to-array";
     }
-    return t.callExpression(this.addHelper(declarationName), args);
+    return t.callExpression(this.addHelper(helperName), args);
   }
 };
 

lib/6to5/transformation/templates/to-array.js

@@ -1,9 +1,3 @@
 (function (arr) {
-  if (Array.isArray(arr)) {
-    var arr2 = [];
-    for (var i = 0; i < arr.length; i++) arr2.push(arr[i]);
-      return arr2;
-  } else {
-    return Array.from(arr);
-  }
+  return Array.isArray(arr) ? arr : Array.from(arr);
 });

lib/6to5/transformation/templates/to-consumable-array.js

@@ -0,0 +1,9 @@
+(function (arr) {
+  if (Array.isArray(arr)) {
+    var arr2 = [];
+    for (var i = 0; i < arr.length; i++) arr2.push(arr[i]);
+      return arr2;
+  } else {
+    return Array.from(arr);
+  }
+});

lib/6to5/transformation/transformers/es6/spread.js

@@ -6,7 +6,7 @@ var t        = require("../../../types");
 exports.check = t.isSpreadElement;
 
 var getSpreadLiteral = function (spread, file) {
-  return file.toArray(spread.argument);
+  return file.toArray(spread.argument, true);
 };
 
 var hasSpread = function (nodes) {