async function should stay on the same line

Fixes #630
Closes #634

js/lib/beautify.js

@@ -641,6 +641,11 @@
                 }
             }
 
+            // Should be a space between await and an IIFE
+            if(current_token.text === '(' && last_type === 'TK_RESERVED' && flags.last_word === 'await'){
+                output.space_before_token = true;
+            }
+
             // Support of this kind of newline preservation.
             // a = (b &&
             //     (c || d));
@@ -862,7 +867,7 @@
                     }
                 }
                 if (last_type === 'TK_RESERVED' || last_type === 'TK_WORD') {
-                    if (last_type === 'TK_RESERVED' && in_array(flags.last_text, ['get', 'set', 'new', 'return', 'export'])) {
+                    if (last_type === 'TK_RESERVED' && in_array(flags.last_text, ['get', 'set', 'new', 'return', 'export', 'async'])) {
                         output.space_before_token = true;
                     } else if (last_type === 'TK_RESERVED' && flags.last_text === 'default' && last_last_text === 'export') {
                         output.space_before_token = true;
@@ -1471,7 +1476,7 @@
 
         // words which should always start on new line.
         this.line_starters = 'continue,try,throw,return,var,let,const,if,switch,case,default,for,while,break,function,import,export'.split(',');
-        var reserved_words = this.line_starters.concat(['do', 'in', 'else', 'get', 'set', 'new', 'catch', 'finally', 'typeof', 'yield']);
+        var reserved_words = this.line_starters.concat(['do', 'in', 'else', 'get', 'set', 'new', 'catch', 'finally', 'typeof', 'yield', 'async', 'await']);
 
         var n_newlines, whitespace_before_token, in_html_comment, tokens, parser_pos;
         var input_length;

js/test/beautify-javascript-tests.js

@@ -292,6 +292,20 @@ function run_javascript_tests(test_obj, Urlencoded, js_beautify, html_beautify,
 
         // New Test Suite
 
+        // Async / await tests
+        bt('async function foo() {}');
+        bt('let w = async function foo() {}');
+        bt('async function foo() {}\nvar x = await foo();');
+
+        // async function as an input to another function
+        bt('wrapper(async function foo() {})');
+
+        // await on inline anonymous function. should have a space after await
+        bt('async function() {\n    var w = await(async function() {\n        return await foo();\n    })();\n}', 'async function() {\n    var w = await (async function() {\n        return await foo();\n    })();\n}');
+
+        // ensure that this doesn't break anyone with the async library
+        bt('async.map(function(t) {})');
+
         // Old tests
         bt('');
         test_fragment('   return .5');

python/jsbeautifier/__init__.py

@@ -616,6 +616,10 @@ def handle_start_expr(self, current_token):
             # TODO: option space_before_conditional
             self.output.space_before_token = True
 
+        elif current_token.text == '(' and self.last_type == 'TK_RESERVED' and self.flags.last_word == 'await':
+            self.output.space_before_token = True
+
+
         # Support of this kind of newline preservation:
         # a = (b &&
         #     (c || d));
@@ -801,7 +805,7 @@ def handle_word(self, current_token):
                     self.print_newline(True)
 
             if self.last_type == 'TK_RESERVED' or self.last_type == 'TK_WORD':
-                if self.last_type == 'TK_RESERVED' and self.flags.last_text in ['get', 'set', 'new', 'return', 'export']:
+                if self.last_type == 'TK_RESERVED' and self.flags.last_text in ['get', 'set', 'new', 'return', 'export', 'async']:
                     self.output.space_before_token = True
                 elif self.last_type == 'TK_RESERVED' and self.flags.last_text == 'default' and self.last_last_text == 'export':
                     self.output.space_before_token = True
@@ -1326,7 +1330,7 @@ class Tokenizer:
 
     # Words which always should start on a new line
     line_starters = 'continue,try,throw,return,var,let,const,if,switch,case,default,for,while,break,function,import,export'.split(',')
-    reserved_words = line_starters + ['do', 'in', 'else', 'get', 'set', 'new', 'catch', 'finally', 'typeof', 'yield']
+    reserved_words = line_starters + ['do', 'in', 'else', 'get', 'set', 'new', 'catch', 'finally', 'typeof', 'yield', 'async', 'await']
 
     def __init__ (self, input, opts, indent_string):
         self.input = input

python/jsbeautifier/tests/testjsbeautifier.py

@@ -112,6 +112,20 @@ def unicode_char(value):
 
         # New Test Suite
 
+        # Async / await tests
+        bt('async function foo() {}')
+        bt('let w = async function foo() {}')
+        bt('async function foo() {}\nvar x = await foo();')
+
+        # async function as an input to another function
+        bt('wrapper(async function foo() {})')
+
+        # await on inline anonymous function. should have a space after await
+        bt('async function() {\n    var w = await(async function() {\n        return await foo();\n    })();\n}', 'async function() {\n    var w = await (async function() {\n        return await foo();\n    })();\n}')
+
+        # ensure that this doesn't break anyone with the async library
+        bt('async.map(function(t) {})')
+
         # Old tests
         bt('')
         test_fragment('   return .5')

test/data/javascript.js

@@ -93,6 +93,27 @@ exports.test_data = {
         ],
     }, {
         name: "New Test Suite"
+    },
+    {
+        name: "Async / await tests",
+        description: "ES7 async / await tests",
+        tests: [
+            { input: "async function foo() {}" },
+            { input: "let w = async function foo() {}" },
+            { input: "async function foo() {}\nvar x = await foo();"},
+            {
+                comment: "async function as an input to another function",
+                input: "wrapper(async function foo() {})"},
+            {
+                comment: "await on inline anonymous function. should have a space after await",
+                input: "async function() {\n    var w = await(async function() {\n        return await foo();\n    })();\n}",
+                output: "async function() {\n    var w = await (async function() {\n        return await foo();\n    })();\n}"
+            },
+            {
+                comment: "ensure that this doesn't break anyone with the async library",
+                input: "async.map(function(t) {})"
+            }
+        ]
     },
         // =======================================================
         // New tests groups should be added above this line.