avoid prototype builtin hasOwnProperty (#2144)

6 files changed, 74 insertions, 7 deletions

diff --git a/js/blob.ts b/js/blob.ts
index c23b74afb..092bfaa08 100644
--- a/js/blob.ts
+++ b/js/blob.ts
@@ -1,6 +1,6 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
 import * as domTypes from "./dom_types";
-import { containsOnlyASCII } from "./util";
+import { containsOnlyASCII, hasOwnProperty } from "./util";
 import { TextEncoder } from "./text_encoding";
 
 export const bytesSymbol = Symbol("bytes");
@@ -91,7 +91,7 @@ export class DenoBlob implements domTypes.Blob {
 
     options = options || {};
     // Set ending property's default value to "transparent".
-    if (!options.hasOwnProperty("ending")) {
+    if (!hasOwnProperty(options, "ending")) {
       options.ending = "transparent";
     }
 
diff --git a/js/blob_test.ts b/js/blob_test.ts
index 1e8ec8fbd..3c778a0e1 100644
--- a/js/blob_test.ts
+++ b/js/blob_test.ts
@@ -32,4 +32,22 @@ test(function blobSlice() {
   assertEquals(b4.size, blob.size);
 });
 
+test(function blobShouldNotThrowError() {
+  let hasThrown = false;
+
+  try {
+    const options1: object = {
+      ending: "utf8",
+      hasOwnProperty: "hasOwnProperty"
+    };
+    const options2: object = Object.create(null);
+    new Blob(["Hello World"], options1);
+    new Blob(["Hello World"], options2);
+  } catch {
+    hasThrown = true;
+  }
+
+  assertEquals(hasThrown, false);
+});
+
 // TODO(qti3e) Test the stored data in a Blob after implementing FileReader API.
diff --git a/js/console_table.ts b/js/console_table.ts
index d7cae124c..43819c5fe 100644
--- a/js/console_table.ts
+++ b/js/console_table.ts
@@ -2,6 +2,7 @@
 // Forked from Node's lib/internal/cli_table.js
 
 import { TextEncoder } from "./text_encoding";
+import { hasOwnProperty } from "./util";
 
 const encoder = new TextEncoder();
 
@@ -64,7 +65,7 @@ export function cliTable(head: string[], columns: string[][]): string {
       if (rows[j] === undefined) {
         rows[j] = [];
       }
-      const value = (rows[j][i] = column.hasOwnProperty(j) ? column[j] : "");
+      const value = (rows[j][i] = hasOwnProperty(column, j) ? column[j] : "");
       const width = columnWidths[i] || 0;
       const counted = countBytes(value);
       columnWidths[i] = Math.max(width, counted);
diff --git a/js/event_target.ts b/js/event_target.ts
index cc436865e..87268383e 100644
--- a/js/event_target.ts
+++ b/js/event_target.ts
@@ -1,6 +1,6 @@
 // Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
 import * as domTypes from "./dom_types";
-import { requiredArguments } from "./util";
+import { requiredArguments, hasOwnProperty } from "./util";
 
 /* TODO: This is an incomplete implementation to provide functionality
  * for Event. A proper spec is still required for a proper Web API.
@@ -16,7 +16,7 @@ export class EventTarget implements domTypes.EventTarget {
     _options?: boolean | domTypes.AddEventListenerOptions
   ): void {
     requiredArguments("EventTarget.addEventListener", arguments.length, 2);
-    if (!this.listeners.hasOwnProperty(type)) {
+    if (!hasOwnProperty(this.listeners, type)) {
       this.listeners[type] = [];
     }
     if (listener !== null) {
@@ -30,7 +30,7 @@ export class EventTarget implements domTypes.EventTarget {
     _options?: domTypes.EventListenerOptions | boolean
   ): void {
     requiredArguments("EventTarget.removeEventListener", arguments.length, 2);
-    if (this.listeners.hasOwnProperty(type) && callback !== null) {
+    if (hasOwnProperty(this.listeners, type) && callback !== null) {
       this.listeners[type] = this.listeners[type].filter(
         listener => listener !== callback
       );
@@ -39,7 +39,7 @@ export class EventTarget implements domTypes.EventTarget {
 
   public dispatchEvent(event: domTypes.Event): boolean {
     requiredArguments("EventTarget.dispatchEvent", arguments.length, 1);
-    if (!this.listeners.hasOwnProperty(event.type)) {
+    if (!hasOwnProperty(this.listeners, event.type)) {
       return true;
     }
     const stack = this.listeners[event.type].slice();
diff --git a/js/event_target_test.ts b/js/event_target_test.ts
index 71c872dab..aedbbf72a 100644
--- a/js/event_target_test.ts
+++ b/js/event_target_test.ts
@@ -92,3 +92,21 @@ test(function toStringShouldBeWebCompatibility() {
   const target = new EventTarget();
   assertEquals(target.toString(), "[object EventTarget]");
 });
+
+test(function dispatchEventShouldNotThrowError() {
+  let hasThrown = false;
+
+  try {
+    const target = new EventTarget();
+    const event = new Event("hasOwnProperty", {
+      bubbles: true,
+      cancelable: false
+    });
+    target.addEventListener("hasOwnProperty", () => {});
+    target.dispatchEvent(event);
+  } catch {
+    hasThrown = true;
+  }
+
+  assertEquals(hasThrown, false);
+});
diff --git a/js/util.ts b/js/util.ts
index e6f38c8e1..b81b96aca 100644
--- a/js/util.ts
+++ b/js/util.ts
@@ -142,3 +142,33 @@ export function getPrivateValue<
   }
   throw new TypeError("Illegal invocation");
 }
+
+/**
+ * Determines whether an object has a property with the specified name.
+ * Avoid calling prototype builtin `hasOwnProperty` for two reasons:
+ *
+ * 1. `hasOwnProperty` is defined on the object as something else:
+ *
+ *      const options = {
+ *        ending: 'utf8',
+ *        hasOwnProperty: 'foo'
+ *      };
+ *      options.hasOwnProperty('ending') // throws a TypeError
+ *
+ * 2. The object doesn't inherit from `Object.prototype`:
+ *
+ *       const options = Object.create(null);
+ *       options.ending = 'utf8';
+ *       options.hasOwnProperty('ending'); // throws a TypeError
+ *
+ * @param obj A Object.
+ * @param v A property name.
+ * @see https://eslint.org/docs/rules/no-prototype-builtins
+ * @internal
+ */
+export function hasOwnProperty<T>(obj: T, v: PropertyKey): boolean {
+  if (obj == null) {
+    return false;
+  }
+  return Object.prototype.hasOwnProperty.call(obj, v);
+}