add destructuring defaults #230

lib/6to5/transformation/transformers/es6-destructuring.js

@@ -21,12 +21,30 @@ var push = function (opts, nodes, elem, parentId) {
   } else if (t.isArrayPattern(elem)) {
     pushArrayPattern(opts, nodes, elem, parentId);
   } else if (t.isAssignmentPattern(elem)) {
-    return;
+    pushAssignmentPattern(opts, nodes, elem, parentId);
   } else {
     nodes.push(buildVariableAssign(opts, elem, parentId));
   }
 };
 
+var pushAssignmentPattern = function (opts, nodes, pattern, parentId) {
+  var tempParentId = opts.scope.generateUidBasedOnNode(parentId, opts.file);
+
+  nodes.push(t.variableDeclaration("var", [
+    t.variableDeclarator(tempParentId, parentId)
+  ]));
+
+  nodes.push(buildVariableAssign(
+    opts,
+    pattern.left,
+    t.conditionalExpression(
+      t.binaryExpression("===", tempParentId, t.identifier("undefined")),
+      pattern.right,
+      tempParentId
+    )
+  ));
+};
+
 var pushObjectPattern = function (opts, nodes, pattern, parentId) {
   for (var i in pattern.properties) {
     var prop = pattern.properties[i];
@@ -187,6 +205,24 @@ exports.Function = function (node, parent, file, scope) {
   block.body = nodes.concat(block.body);
 };
 
+exports.CatchClause = function (node, parent, file, scope) {
+  var pattern = node.param;
+  if (!t.isPattern(pattern)) return;
+
+  var ref = file.generateUidIdentifier("ref", scope);
+  node.param = ref;
+
+  var nodes = [];
+
+  push({
+    kind: "var",
+    file: file,
+    scope: scope
+  }, nodes, pattern, ref);
+
+  node.body.body = nodes.concat(node.body.body);
+};
+
 exports.ExpressionStatement = function (node, parent, file, scope) {
   var expr = node.expression;
   if (expr.type !== "AssignmentExpression") return;