Add freeze

lib/freeze.js

@@ -0,0 +1,32 @@
+function isFreezable(obj) {
+  if (Object.isFrozen(obj)) {
+    return false;
+  }
+
+  return Array.isArray(obj) || typeof obj === 'object';
+}
+
+function recur(obj) {
+  Object.freeze(obj);
+
+  Object.keys(obj).forEach((key) => {
+    const value = obj[key];
+    if (isFreezable(value)) {
+      recur(value);
+    }
+  });
+
+  return obj;
+}
+
+export default function freeze(obj) {
+  if (process.env.NODE_ENV === 'production') {
+    return obj;
+  }
+
+  if (isFreezable(obj)) {
+    recur(obj);
+  }
+
+  return obj;
+}

test/.eslintrc

@@ -0,0 +1,5 @@
+{
+  "rules": {
+    "no-unused-expressions": 0
+  }
+}

test/freeze.js

@@ -0,0 +1,53 @@
+import { expect } from 'chai';
+import freeze from '../lib/freeze';
+
+describe('freeze', () => {
+  afterEach(() => {
+    delete process.env.NODE_ENV;
+  });
+
+  it('freezes objects', () => {
+    const obj = {};
+    freeze(obj);
+
+    expect(Object.isFrozen(obj)).to.be.true;
+  });
+
+  it('freezes nested objects', () => {
+    const obj = { foo: { bar: 3 } };
+    freeze(obj);
+
+    expect(Object.isFrozen(obj.foo)).to.be.true;
+  });
+
+  it('freezes nested arrays', () => {
+    const obj = [[0]];
+    freeze(obj);
+
+    expect(Object.isFrozen(obj)).to.be.true;
+    expect(Object.isFrozen(obj[0])).to.be.true;
+  });
+
+  it('ignores functions', () => {
+    const obj = { foo: () => 1 };
+    freeze(obj);
+
+    expect(Object.isFrozen(obj.foo)).to.be.false;
+  });
+
+  it('does not freeze children if the parent is already frozen', () => {
+    const obj = { foo: {} };
+    Object.freeze(obj);
+    freeze(obj);
+
+    expect(Object.isFrozen(obj.foo)).to.be.false;
+  });
+
+  it('does not freeze in production', () => {
+    process.env.NODE_ENV = 'production';
+    const obj = {};
+    freeze(obj);
+
+    expect(Object.isFrozen(obj)).to.be.false;
+  });
+});