util: add type check functions for BigInt arrays

Adds `isBigInt64Array` and `isBigUint64Array`.

PR-URL: https://github.com/nodejs/node/pull/19201
Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

lib/internal/util/types.js

@@ -61,6 +61,14 @@ function isFloat64Array(value) {
   return TypedArrayProto_toStringTag(value) === 'Float64Array';
 }
 
+function isBigInt64Array(value) {
+  return TypedArrayProto_toStringTag(value) === 'BigInt64Array';
+}
+
+function isBigUint64Array(value) {
+  return TypedArrayProto_toStringTag(value) === 'BigUint64Array';
+}
+
 module.exports = {
   isArrayBufferView,
   isTypedArray,
@@ -72,5 +80,7 @@ module.exports = {
   isInt16Array,
   isInt32Array,
   isFloat32Array,
-  isFloat64Array
+  isFloat64Array,
+  isBigInt64Array,
+  isBigUint64Array
 };

test/.eslintrc.yaml

@@ -21,3 +21,5 @@ rules:
 # Global scoped methods and vars
 globals:
   WebAssembly: false
+  BigInt64Array: false
+  BigUint64Array: false

test/parallel/test-util-types.js

@@ -1,3 +1,4 @@
+// Flags: --harmony-bigint
 /* global SharedArrayBuffer */
 'use strict';
 const common = require('../common');
@@ -44,6 +45,8 @@ for (const [ value, _method ] of [
   [ new Int32Array() ],
   [ new Float32Array() ],
   [ new Float64Array() ],
+  [ new BigInt64Array() ],
+  [ new BigUint64Array() ],
   [ Object.defineProperty(new Uint8Array(),
                           Symbol.toStringTag,
                           { value: 'foo' }) ],