js: snapshot comments / flow type additions

lib/modules/database/snapshot.js

@@ -4,6 +4,9 @@
 import Reference from './reference.js';
 import { isObject, deepGet, deepExists } from './../../utils';
 
+/**
+ * @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot
+ */
 export default class Snapshot {
   static key: String;
   static value: Object;
@@ -52,6 +55,7 @@ export default class Snapshot {
       value,
       key: childRef.key,
       exists: value !== null,
+
       // todo this is wrong - child keys needs to be the ordered keys, from FB
       // todo potential solution is build up a tree/map of a snapshot and its children
       // todo natively and send that back to JS to be use in this class.
@@ -91,33 +95,50 @@ export default class Snapshot {
     return cancelled;
   }
 
-  getPriority() {
+  /**
+   * Gets the priority value of the data in this DataSnapshot.
+   * @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#getPriority
+   * @returns {String|Number|null}
+   */
+  getPriority(): String|Number|null {
     return this.priority;
   }
 
-  hasChild(path: string) {
+  /**
+   * Returns true if the specified child path has (non-null) data.
+   * @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#hasChild
+   * @param path
+   * @returns {Boolean}
+   */
+  hasChild(path: string): Boolean {
     return deepExists(this.value, path);
   }
 
-  hasChildren() {
+  /**
+   * Returns whether or not the DataSnapshot has any non-null child properties.
+   * @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#hasChildren
+   * @returns {boolean}
+   */
+  hasChildren(): Boolean {
     return this.numChildren() > 0;
   }
 
-  numChildren() {
+  /**
+   * Returns the number of child properties of this DataSnapshot.
+   * @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#numChildren
+   * @returns {Number}
+   */
+  numChildren(): Number {
     if (!isObject(this.value)) return 0;
     return Object.keys(this.value).length;
   }
 
-  /*
-   * EXTRA API METHODS
+  /**
+   * Returns a JSON-serializable representation of this object.
+   * @link https://firebase.google.com/docs/reference/js/firebase.database.DataSnapshot#toJSON
+   * @returns {any}
    */
-  map(fn: (key: string) => mixed) {
-    const arr = [];
-    this.forEach((item, i) => arr.push(fn(item, i)));
-    return arr;
-  }
-
-  reverseMap(fn: (key: string) => mixed) {
-    return this.map(fn).reverse();
+  toJSON(): any {
+    return this.val();
   }
 }