Fix handling null differently than undefined.

`u` and friends will now coerce null to an object if there are updates for it.

Fixes #20

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## [unreleased]
 * Add `u._` placeholder for curried functions.
+* Fix handling null differently than undefined. `u` and friends will now coerce null to an object if there are updates for it. (https://github.com/substantial/updeep/issues/20)
 
 ## [0.6.0]
 * Remove support for `_.placeholder` in curried methods. This may come back, but it was necessary for the next item.

lib/update.js

@@ -10,7 +10,7 @@ function reduce(object, callback, initialValue) {
   }, initialValue);
 }
 
-function resolveUpdates(updates, object = {}) {
+function resolveUpdates(updates, object) {
   return reduce(updates, (acc, value, key) => {
     let updatedValue = value;
 
@@ -62,17 +62,21 @@ function update(updates, object, ...args) {
     return updates;
   }
 
-  const resolvedUpdates = resolveUpdates(updates, object);
+  const defaultedObject = (typeof object === 'undefined' || object === null) ?
+    {} :
+    object;
+
+  const resolvedUpdates = resolveUpdates(updates, defaultedObject);
 
   if (isEmpty(resolvedUpdates)) {
     return object;
   }
 
-  if (Array.isArray(object)) {
-    return updateArray(resolvedUpdates, object);
+  if (Array.isArray(defaultedObject)) {
+    return updateArray(resolvedUpdates, defaultedObject);
   }
 
-  return { ...object, ...resolvedUpdates };
+  return { ...defaultedObject, ...resolvedUpdates };
 }
 
 export default wrap(update, 2);

test/updeep-spec.js

@@ -118,4 +118,15 @@ describe('updeep', () => {
 
     expect(result).to.eql({ name: 'Joe Merrill', age: 22 });
   });
+
+  it('defaults to an empty object when null or undefined', () => {
+    let result = u({ a: { b: 0 } }, { a: null });
+    expect(result).to.eql({ a: { b: 0 } });
+
+    result = u({ a: { b: 0 } }, { a: undefined });
+    expect(result).to.eql({ a: { b: 0 } });
+
+    result = u({ a: { b: 0 } }, { });
+    expect(result).to.eql({ a: { b: 0 } });
+  });
 });