Fix #82 - Added Record.has(key)

Added: had method of Record to check if a value exists before using it
Added: tests for the has method

Author: Stefan-Gabriel Muscalu

src/v1/record.js

@@ -100,6 +100,22 @@ class Record {
 
     return this._fields[index];
   }
+
+  /**
+   * Check if a value from this record, either by index or by field key, exists.
+   *
+   * @param {string|Number} key Field key, or the index of the field.
+   * @returns {boolean}
+   */
+  has( key ) {
+    // if key is a number, we check if it is in the _fields array
+    if( typeof key === "number" ) {
+      return ( key >= 0 && key < this._fields.length );
+    }
+
+    // if it's not a number, we check _fieldLookup dictionary directly
+    return this._fieldLookup[key] !== undefined;
+  }
 }
 
 export {Record}

test/v1/record.test.js

@@ -30,6 +30,17 @@ describe('Record', function() {
     expect(record.get("name")).toEqual("Bob");
   });
 
+  it('should allow checking if fields exist', function() {
+    // Given
+    var record = new Record( ["name"], ["Bob"] );
+
+    // When & Then
+    expect(record.has("name")).toEqual(true);
+    expect(record.has("invalid key")).toEqual(false);
+    expect(record.has(0)).toEqual(true);
+    expect(record.has(1)).toEqual(false);
+  });
+
   it('should give helpful error on no such key', function() {
     // Given
     var record = new Record( ["name"], ["Bob"] );