Add support for tailing comma

npm/index.js

@@ -340,6 +340,10 @@ function* parseJson(stdin) {
       } else if (lastChar === ',') {
         next()
         skipWhitespace()
+        if (lastChar === '}') {
+          next()
+          return obj
+        }
       } else {
         throw new SyntaxError(errorSnippet())
       }
@@ -366,6 +370,10 @@ function* parseJson(stdin) {
       } else if (lastChar === ',') {
         next()
         skipWhitespace()
+        if (lastChar === ']') {
+          next()
+          return array
+        }
       } else {
         throw new SyntaxError(errorSnippet())
       }

npm/test.js

@@ -23,7 +23,6 @@ void async function main() {
     t.deepEqual(stdout, '[\n  {\n    "greeting": "hello world"\n  }\n]\n')
   })
 
-
   await test('parseJson - valid json', async t => {
     const obj = {a: 2.3e100, b: 'str', c: null, d: false, e: [1, 2, 3]}
     const {stdout, stderr} = await run(obj)
@@ -60,6 +59,16 @@ void async function main() {
     t.equal((await run('2.3e-3')).stdout, '0.0023\n')
   })
 
+  await test('parseJson - object tailing comma', async t => {
+    const {stdout} = await run('{"a": 1,}')
+    t.equal(stdout, '{\n  "a": 1\n}\n')
+  })
+
+  await test('parseJson - array tailing comma', async t => {
+    const {stdout} = await run('[1,]')
+    t.equal(stdout, '[\n  1\n]\n')
+  })
+
   await test('transform - anonymous function', async t => {
     const {stdout} = await run({'key': 'value'}, '\'function (x) { return x.key }\'')
     t.equal(stdout, 'value\n')