feat: add xor function

README.md

@@ -13,6 +13,8 @@ Some utility functions to make dealing with `Uint8Array`s more pleasant.
     - [Example](#example-3)
   - [toString(array, encoding = 'utf8')](#tostringarray-encoding--utf8)
     - [Example](#example-4)
+  - [xor(a, b)](#xora-b)
+    - [Example](#example-5)
 
 ## API
 
@@ -112,3 +114,15 @@ console.info(toString(Uint8Array.from([0, 1, 2...]), 'base16')) // '00010203aabb
 console.info(toString(Uint8Array.from([0, 1, 2...]), 'base64')) // 'AAECA6q7zA'
 console.info(toString(Uint8Array.from([48, 49, 50...]), 'ascii')) // '01234'
 ```
+
+### xor(a, b)
+
+Returns a `Uint8Array` containing `a` and `b` xored together.
+
+#### Example
+
+```js
+const xor = require('uint8arrays/xor')
+
+console.info(xor(Uint8Array.from([1, 0]), Uint8Array.from([0, 1]))) // Uint8Array[1, 1]
+```

package.json

@@ -22,6 +22,7 @@
     "from-string.js",
     "index.js",
     "to-string.js",
+    "xor.js",
     "dist/*.ts",
     "dist/*.map",
     "dist/*.js"
@@ -46,7 +47,7 @@
     "web-encoding": "^1.0.5"
   },
   "devDependencies": {
-    "aegir": "^30.1.0"
+    "aegir": "^30.3.0"
   },
   "contributors": [
     "achingbrain <alex@achingbrain.net>",

test/compare.spec.js

@@ -1,6 +1,6 @@
+/* eslint-env mocha */
 'use strict'
 
-/* eslint-env mocha */
 const { expect } = require('aegir/utils/chai')
 const compare = require('../compare')
 

test/concat.spec.js

@@ -1,6 +1,6 @@
+/* eslint-env mocha */
 'use strict'
 
-/* eslint-env mocha */
 const { expect } = require('aegir/utils/chai')
 const concat = require('../concat')
 

test/equals.spec.js

@@ -1,6 +1,6 @@
+/* eslint-env mocha */
 'use strict'
 
-/* eslint-env mocha */
 const { expect } = require('aegir/utils/chai')
 const equals = require('../equals')
 

test/from-string.spec.js

@@ -1,6 +1,6 @@
+/* eslint-env mocha */
 'use strict'
 
-/* eslint-env mocha */
 const { expect } = require('aegir/utils/chai')
 const fromString = require('../from-string')
 const { TextEncoder } = require('web-encoding')

test/to-string.spec.js

@@ -1,8 +1,6 @@
-'use strict'
-
 /* eslint-env mocha */
+'use strict'
 
-// @ts-ignore
 const { expect } = require('aegir/utils/chai')
 const toString = require('../to-string')
 const { TextEncoder } = require('web-encoding')

test/xor.spec.js

@@ -0,0 +1,28 @@
+/* eslint-env mocha */
+'use strict'
+
+const { expect } = require('aegir/utils/chai')
+const xor = require('../xor')
+
+describe('Uint8Array xor', () => {
+  it('xors 1,0 and 0,1', () => {
+    const a = Uint8Array.from([1, 0])
+    const b = Uint8Array.from([0, 1])
+
+    expect(xor(a, b)).to.deep.equal(Uint8Array.from([1, 1]))
+  })
+
+  it('xors 1,1 and 0,1', () => {
+    const a = Uint8Array.from([1, 1])
+    const b = Uint8Array.from([0, 1])
+
+    expect(xor(a, b)).to.deep.equal(Uint8Array.from([1, 0]))
+  })
+
+  it('xors 1,1 and 1,1', () => {
+    const a = Uint8Array.from([1, 1])
+    const b = Uint8Array.from([1, 1])
+
+    expect(xor(a, b)).to.deep.equal(Uint8Array.from([0, 0]))
+  })
+})

tsconfig.json

@@ -4,7 +4,7 @@
         "outDir": "dist"
     },
     "include": [
-      "test", // remove this line if you don't want to type-check tests
+      "test",
       "*.js"
     ]
 }

xor.js

@@ -0,0 +1,24 @@
+'use strict'
+
+/**
+ * Returns the xor distance between two arrays
+ *
+ * @param {Uint8Array} a
+ * @param {Uint8Array} b
+ * @returns {Uint8Array}
+ */
+function xor (a, b) {
+  if (a.length !== b.length) {
+    throw new Error('Inputs should have the same length')
+  }
+
+  const result = new Uint8Array(a.length)
+
+  for (let i = 0; i < a.length; i++) {
+    result[i] = a[i] ^ b[i]
+  }
+
+  return result
+}
+
+module.exports = xor