Add .filter/.filterBy methods

index.js

@@ -10,6 +10,16 @@ module.exports = class Query {
     return this.data;
   };
 
+  filter (func) {
+    this.data = this.data.filter(func);
+    return this;
+  };
+
+  filterBy (key, func) {
+    this.data = this.data.filter(item => func(item[key]));
+    return this;
+  };
+
   search (key, term, score = 0) {
     switch (typeof term) {
       case 'boolean':

index.test.js

@@ -66,6 +66,26 @@ test('should sort by string name', () => {
   expect(query[0].name).toBe('Dudley Conner');
 });
 
+test('should filter', () => {
+  let isAgeOver33 = a => a.age > 33;
+
+  let query = new Query(TestData)
+  .filter(isAgeOver33)
+  .results;
+
+  expect(query[0].name).toBe('Howard Buckley');
+});
+
+test('should filter by key', () => {
+  let isNumGT33 = num => num > 33;
+
+  let query = new Query(TestData)
+  .filterBy('age', isNumGT33)
+  .results;
+
+  expect(query[0].name).toBe('Howard Buckley');
+});
+
 test('should chain everything together', () => {
   let query = new Query(TestData)
   .search('isActive', true)