Use isArray instead of constructor check - fixes #28

Author: dmonad

array.test.js

@@ -1,6 +1,43 @@
 import * as array from './array.js'
 import * as t from './testing.js'
 
+/**
+ * @param {t.TestCase} _tc
+ */
+export const testIsarrayPerformance = _tc => {
+  const N = 100000
+  /**
+   * @type {Array<any>}
+   */
+  const objects = []
+  for (let i = 0; i < N; i++) {
+    if (i % 2 === 0) {
+      objects.push([i])
+    } else {
+      objects.push({ i })
+    }
+  }
+  const timeConstructor = t.measureTime('constructor check', () => {
+    let collectedArrays = 0
+    objects.forEach(obj => {
+      if (obj.constructor === Array) {
+        collectedArrays++
+      }
+    })
+    t.assert(collectedArrays === N / 2)
+  })
+  const timeIsarray = t.measureTime('Array.isArray', () => {
+    let collectedArrays = 0
+    objects.forEach(obj => {
+      if (array.isArray(obj)) {
+        collectedArrays++
+      }
+    })
+    t.assert(collectedArrays === N / 2)
+  })
+  t.assert(timeIsarray < timeConstructor * 1.3, 'Expecting that isArray is not much worse than a constructor check')
+}
+
 /**
  * @param {t.TestCase} _tc
  */

encoding.js

@@ -31,6 +31,7 @@ import * as math from './math.js'
 import * as number from './number.js'
 import * as binary from './binary.js'
 import * as string from './string.js'
+import * as array from './array.js'
 
 /**
  * A BinaryEncoder handles the encoding to an Uint8Array.
@@ -513,7 +514,7 @@ export const writeAny = (encoder, data) => {
       if (data === null) {
         // TYPE 126: null
         write(encoder, 126)
-      } else if (data instanceof Array) {
+      } else if (array.isArray(data)) {
         // TYPE 117: Array
         write(encoder, 117)
         writeVarUint(encoder, data.length)

function.js

@@ -58,7 +58,7 @@ export const equalityStrict = (a, b) => a === b
  * @param {Array<T>|object} b
  * @return {boolean}
  */
-export const equalityFlat = (a, b) => a === b || (a != null && b != null && a.constructor === b.constructor && ((a instanceof Array && array.equalFlat(a, /** @type {Array<T>} */ (b))) || (typeof a === 'object' && object.equalFlat(a, b))))
+export const equalityFlat = (a, b) => a === b || (a != null && b != null && a.constructor === b.constructor && ((array.isArray(a) && array.equalFlat(a, /** @type {Array<T>} */ (b))) || (typeof a === 'object' && object.equalFlat(a, b))))
 
 /* c8 ignore start */