Add support for loconfig.local.json

If a 'loconfig.local.json' file is present (ignored by git), its settings will be merged with those in 'loconfig.json'. Useful for customizing localhost development (see example below).

Added:
- Utility 'config.js' to prepare build settings.
- Function 'merge()' for recursively merging objects and concatenating arrays.

Example:

```json
{
    "paths": {
        "url": "yourlocal.dev"
    },
    "server": {
        "open": true,
        "https": {
            "key": "~/.config/valet/Certificates/{% paths.url %}.key",
            "cert": "~/.config/valet/Certificates/{% paths.url %}.crt"
        }
    }
}
```

build/tasks/concats.js

@@ -1,4 +1,4 @@
-import loconfig from '../../loconfig.json';
+import loconfig from '../utils/config.js';
 import glob from '../utils/glob.js';
 import message from '../utils/message.js';
 import notification from '../utils/notification.js';

build/tasks/scripts.js

@@ -1,4 +1,4 @@
-import loconfig from '../../loconfig.json';
+import loconfig from '../utils/config.js';
 import message from '../utils/message.js';
 import notification from '../utils/notification.js';
 import resolve from '../utils/template.js';

build/tasks/styles.js

@@ -1,4 +1,4 @@
-import loconfig from '../../loconfig.json';
+import loconfig from '../utils/config.js';
 import message from '../utils/message.js';
 import notification from '../utils/notification.js';
 import postcss, { pluginsMap as postcssPluginsMap } from '../utils/postcss.js';

build/tasks/svgs.js

@@ -1,4 +1,4 @@
-import loconfig from '../../loconfig.json';
+import loconfig from '../utils/config.js';
 import message from '../utils/message.js';
 import notification from '../utils/notification.js';
 import resolve from '../utils/template.js';

build/utils/config.js

@@ -0,0 +1,64 @@
+/**
+ * @file Provides simple user configuration options.
+ */
+
+import loconfig from '../../loconfig.json';
+
+let usrconfig;
+
+try {
+    usrconfig = await import('../../loconfig.local.json');
+    usrconfig = usrconfig.default;
+
+    merge(loconfig, usrconfig);
+} catch (err) {
+    // do nothing
+}
+
+export default loconfig;
+
+/**
+ * Creates a new object with all nested object properties
+ * merged into it recursively.
+ *
+ * @param  {object}   target     - The target object.
+ * @param  {object[]} ...sources - The source object(s).
+ * @throws {TypeError} If the target and source are the same.
+ * @return {object} Returns the `target` object.
+ */
+export function merge(target, ...sources) {
+    for (const source of sources) {
+        if (target === source) {
+            throw new TypeError(
+                'Cannot merge, target and source are the same'
+            );
+        }
+
+        for (const key in source) {
+            if (source[key] != null) {
+                if (isObjectLike(source[key]) && isObjectLike(target[key])) {
+                    merge(target[key], source[key]);
+                    continue;
+                } else if (Array.isArray(source[key]) && Array.isArray(target[key])) {
+                    target[key] = target[key].concat(source[key]);
+                    continue;
+                }
+            }
+
+            target[key] = source[key];
+        }
+    }
+
+    return target;
+}
+
+/**
+ * Determines whether the passed value is an `Object`.
+ *
+ * @param  {*} value - The value to be checked.
+ * @return {boolean} Returns `true` if the value is an `Object`,
+ *     otherwise `false`.
+ */
+function isObjectLike(value) {
+    return (value != null && typeof value === 'object');
+}

build/utils/template.js

@@ -2,7 +2,7 @@
  * @file Provides simple template tags.
  */
 
-import loconfig from '../../loconfig.json';
+import loconfig from './config.js';
 
 const templateData = flatten({
     paths: loconfig.paths

build/watch.js

@@ -1,8 +1,8 @@
-import loconfig from '../loconfig.json';
 import concatFiles, { developmentConcatFilesArgs } from './tasks/concats.js';
 import compileScripts, { developmentScriptsArgs } from './tasks/scripts.js';
 import compileStyles, { developmentStylesArgs } from './tasks/styles.js' ;
 import compileSVGs, { developmentSVGsArgs } from './tasks/svgs.js';
+import loconfig, { merge } from './utils/config.js';
 import message from './utils/message.js';
 import notification from './utils/notification.js';
 import resolve from './utils/template.js';
@@ -124,9 +124,7 @@ function createServerOptions({
         };
     }
 
-    Object.assign(config, resolve(options));
-
-    return config;
+    return merge(config, resolve(options));
 }
 
 /**