Prefer 'in' over 'hasOwnProperty' when safe.

- Static '@' keywords should be safe to use with 'in'.

Author: davidlehn

lib/context.js

@@ -1284,12 +1284,12 @@ api.getContextValue = (ctx, key, type) => {
   }
 
   // get default language
-  if(type === '@language' && ctx.hasOwnProperty(type)) {
+  if(type === '@language' && type in ctx) {
     return ctx[type];
   }
 
   // get default direction
-  if(type === '@direction' && ctx.hasOwnProperty(type)) {
+  if(type === '@direction' && type in ctx) {
     return ctx[type];
   }
 

lib/frame.js

@@ -271,7 +271,7 @@ api.frame = (state, subjects, frame, parent, property = null) => {
       // skip keywords
       if(prop === '@type') {
         if(!types.isObject(frame[prop][0]) ||
-           !frame[prop][0].hasOwnProperty('@default')) {
+           !('@default' in frame[prop][0])) {
           continue;
         }
         // allow through default types
@@ -344,7 +344,7 @@ api.cleanupNull = (input, options) => {
 
   if(types.isObject(input)) {
     // handle in-memory linked nodes
-    if(input.hasOwnProperty('@id')) {
+    if('@id' in input) {
       const id = input['@id'];
       if(options.link.hasOwnProperty(id)) {
         const idx = options.link[id].indexOf(input);
@@ -451,7 +451,7 @@ function _validateFrame(frame) {
       'jsonld.SyntaxError', {frame});
   }
 
-  if(frame[0].hasOwnProperty('@id')) {
+  if('@id' in frame[0]) {
     for(const id of util.asArray(frame[0]['@id'])) {
       // @id must be wildcard or an IRI
       if(!(types.isObject(id) || url.isAbsolute(id)) ||
@@ -463,7 +463,7 @@ function _validateFrame(frame) {
     }
   }
 
-  if(frame[0].hasOwnProperty('@type')) {
+  if('@type' in frame[0]) {
     for(const type of util.asArray(frame[0]['@type'])) {
       // @id must be wildcard or an IRI
       if(!(types.isObject(type) || url.isAbsolute(type)) ||
@@ -720,7 +720,7 @@ function _cleanupPreserve(input, options) {
     }
 
     // handle in-memory linked nodes
-    if(input.hasOwnProperty('@id')) {
+    if('@id' in input) {
       const id = input['@id'];
       if(options.link.hasOwnProperty(id)) {
         const idx = options.link[id].indexOf(input);