feat(joinFilter): add a filter to join collections into a string

Author: eliorb

src/_filter/collection/join.js

@@ -0,0 +1,23 @@
+/**
+ * @ngdoc filter
+ * @name join
+ * @kind function
+ *
+ * @description
+ * join a collection by a provided delimiter (space by default)
+ */
+angular.module('a8m.join', [])
+  .filter('join', function () {
+    'use strict';
+    return function (input, delimiter) {
+      if (isUndefined(input) || !isArray(input)) {
+        return input;
+      }
+      if (!delimiter) {
+        delimiter = ' ';
+      }
+
+      return input.join(delimiter);
+    };
+  })
+;

test/spec/filter/collection/join.js

@@ -0,0 +1,78 @@
+'use strict';
+
+describe('isJoinFilter', function () {
+  var joinFilter;
+
+  beforeEach(module('a8m.join'));
+
+  beforeEach(inject(function (_joinFilter_) {
+    joinFilter = _joinFilter_;
+  }));
+
+  describe('given a collection', function () {
+    var arr;
+
+    describe('which is empty', function () {
+      beforeEach(function () {
+        arr = [];
+      });
+
+      it('should return an empty string', function () {
+        expect(joinFilter(arr)).toEqual('');
+      });
+
+    });
+
+    describe('of strings', function () {
+      beforeEach(function () {
+        arr = ['hello', 'world'];
+      });
+
+      describe('with no delimiter', function () {
+        it('should join elements with a space', function () {
+          expect(joinFilter(arr)).toEqual('hello world');
+        });
+      });
+
+      describe('with a custom delimiter', function () {
+        var delim;
+
+        describe('which is not a string', function () {
+          it('should join elements with a toString representation of the delimiter', function () {
+            delim = true;
+            expect(joinFilter(arr, delim)).toEqual('hellotrueworld');
+
+            delim = 10;
+            expect(joinFilter(arr, delim)).toEqual('hello10world');
+
+            delim = {toString: function () { return ' - ' }}
+            expect(joinFilter(arr, delim)).toEqual('hello - world');
+          });
+        });
+
+        it('should join elements with the given delimiter', function () {
+          delim = ', '
+          expect(joinFilter(arr, delim)).toEqual('hello, world');
+        });
+      });
+    });
+
+  });
+
+  describe('given something that is not a collection', function () {
+    var str, obj, bool, num;
+    beforeEach(function () {
+      str = 'string';
+      obj = {'a': 'b'};
+      bool = true;
+      num = 5;
+    });
+
+    it('should return the input as is', function () {
+      expect(joinFilter(str)).toEqual(str);
+      expect(joinFilter(obj)).toEqual(obj);
+      expect(joinFilter(bool)).toEqual(bool);
+      expect(joinFilter(num)).toEqual(num);
+    });
+  });
+});