Refactor code

.babelrc

@@ -0,0 +1,3 @@
+{
+  "presets": ["@babel/preset-env"]
+}

README.md

@@ -7,6 +7,7 @@ Currently detects
 - changes to all parameters within each style layer
 - changes to the layer stack (new, removed, moved layers)
 - changes to sources (new, removed, updated sources)
+- changes to root properties of `glyphs`, `sprite`, `fog`, `terrain`, `id`, `name`, `light`
 
 To be implemented
 
@@ -17,6 +18,138 @@ To be implemented
 
 `bin/mapbox-gl-style-diff ./path/to/style/a.json ./path/to/style/b.json`
 
-## Standalone tool
+## Output
 
-Currently you can also use this as a standalone tool via `stamen-diff.html`
+The output is a JSON in the format of:
+
+```js
+{
+  root: {},
+  layerProps: {},
+  layers: {},
+  sources: {}
+}
+```
+
+Within this, the expected output for each section is:
+
+### Layer props
+
+```js
+{
+    [layer id]: {
+        [property type (layout or paint)]: {
+            [property id]: {
+                type: 'add' | 'remove' | 'move' | 'update',
+                before: <previous value>,
+                after: <next value>
+            }
+        }
+    }
+}
+```
+
+### Layers
+
+#### Add
+
+```js
+{
+    [layer id]: {
+        type: 'add',
+        layer: <layer object>,
+        layerAbove: <id of layer above where added layer is slotted>
+    }
+}
+```
+
+#### Remove
+
+```js
+{
+    [layer id]: {
+        type: 'remove',
+    }
+}
+```
+
+#### Move
+
+```js
+{
+    [layer id]: {
+        type: 'move',
+        layerAbove: <id of layer above where moved layer is slotted>
+    }
+}
+```
+
+### Sources
+
+#### Add
+
+```js
+{
+    [source id]: {
+        type: 'add',
+        source: <layer object>
+    }
+}
+```
+
+#### Remove
+
+```js
+{
+    [source id]: {
+        type: 'remove',
+    }
+}
+```
+
+#### Update
+
+```js
+{
+    [source id]: {
+        type: 'update',
+        before: <previous value>,
+        after: <next value>
+    }
+}
+```
+
+### Root
+
+#### Add
+
+```js
+{
+    [root property]: {
+        type: 'add',
+        value: <root property value>
+    }
+}
+```
+
+#### Remove
+
+```js
+{
+    [root property]: {
+        type: 'remove',
+    }
+}
+```
+
+#### Update
+
+```js
+{
+    [root property]: {
+        type: 'update',
+        before: <previous value>,
+        after: <next value>
+    }
+}
+```