fix(markdown-scope): throw exception when using a reserved word as a …

…scope variable

README.md

@@ -199,6 +199,7 @@ Do you want to write a new one? Read the [plugins readme](./plugins/README.md).
 - [normalize-path](https://github.com/jonschlinkert/normalize-path): Normalize file path slashes to be unix-like forward slashes. Also condenses repeat slashes to a single slash and removes and trailing slashes.
 - [relative](https://github.com/jonschlinkert/relative): Get the relative filepath from path A to path B. Calculates from file-to-directory, file-to-file, directory-to-file, and directory-to-directory.
 - [remark-mos](https://github.com/zkochan/remark-mos): Inject parts of markdown via hidden JavaScript snippets
+- [reserved-words](https://github.com/zxqfox/reserved-words): ECMAScript reserved words checker
 - [resolve](https://github.com/substack/node-resolve): resolve like require.resolve() on behalf of files asynchronously and synchronously
 - [run-async](https://github.com/sboudrias/run-async): Utility method to run function either synchronously or asynchronously using the common `this.async()` style.
 - [tape](https://github.com/substack/tape): tap-producing test harness for node and browsers

lib/create-md-scope.js

@@ -2,6 +2,7 @@
 module.exports = createMDScope
 
 const runAsync = require('run-async')
+const reserved = require('reserved-words')
 
 function createMDScope (plugins, markdown) {
   return Promise.all(
@@ -10,6 +11,14 @@ function createMDScope (plugins, markdown) {
         .map(plugin => plugin(markdown))
     )
     .then(scopes => scopes.reduce(
-      (scope, pluginScope) => Object.assign(scope, pluginScope), {})
+      (scope, pluginScope) => {
+        Object.keys(pluginScope).forEach(scopeVar => {
+          if (reserved.check(scopeVar, 'next')) { // TODO: make it strict
+            throw new Error(`Cannot make '${scopeVar}' a scope variable because it is a reserved word`)
+          }
+          scope[scopeVar] = pluginScope[scopeVar]
+        })
+        return scope
+      }, {})
     )
 }

lib/create-md-scope.spec.js

@@ -22,4 +22,13 @@ describe('createMDScope', () => {
         })
       })
   })
+
+  it('should throw error if the scope variable is a reserved word', done => {
+    createMDScope([() => ({ delete: 1 })], {})
+      .catch(err => {
+        expect(err).to.be.instanceof(Error)
+        expect(err.message).to.eq("Cannot make 'delete' a scope variable because it is a reserved word")
+        done()
+      })
+  })
 })

package.json

@@ -75,6 +75,7 @@
     "normalize-path": "~2.0.1",
     "relative": "~3.0.2",
     "remark-mos": "^1.3.0",
+    "reserved-words": "^0.1.1",
     "resolve": "~1.1.7",
     "run-async": "~2.2.0",
     "tape": "~4.5.1"