What to hand in, and how to hand it in

Make a directory ~fcshome/cs2613/assigments/A3 (i.e. in your git repo for this class). All files related to this assigment should be saved in that directory.
Make sure you commit and push all your work using coursegit before 5PM on Friday October 19.

Marking

This assignment will be worth 5% of your final grade.
You will be marked on the last version pushed to coursegit
You will be marked on

coding style

Follow the Crockford style guide

correctness and implimentation detail

You are asked to impliment things in a specific way in Part 1.

functional javascript

Part of the point of the assignment is to see that a certain tasks can be accomplished in a very similar way in JavaScript as in Racket. So don't go crazy with mutation.
For detailed marking scheme, see javascript-assignment.

Part 1: Flatten

Write a function flatten that produces an array containing all of the elements of all of the nested arrays in an array. For full marks your solution should use recursion. Your function should pass the following jasmine tests

describe("flatten",
     function () {
         it("base case",
        function () {
            expect(ms.flatten([])).toEqual([]);
        });
         it("single element",
        function () {
            expect(ms.flatten([1])).toEqual([1]);
            expect(ms.flatten(["foo"])).toEqual(["foo"]);
            expect(ms.flatten([{foo: 1}])).toEqual([{foo: 1}]);                     
        });
         it("longer list, no mutation",
        function () {
            var data = [[[1],2,[3]],4,[5,6]];
            var orig_data = data;
            expect(ms.flatten(data)).toEqual([1,2,3,4,5,6]);
            expect(data).toEqual(orig_data);
        });
     });

Part 2: Mail Summarize, Again

For this part use the same 3 sample JSON files as for assignment 2.
Write a function summarize_mail that reads one of these JSON files and returns a list of objects with with the specified properties. I recommend using the function flatten from Part 1. You will probably also want to borrow the function read json file. Your function should pass the following tests.

describe("summarize_mail",
     function() {
         it("no headers",
        function () {
            expect(ms.summarize_mail("example1.json")).toEqual([{}, {}, {}]);
            expect(ms.summarize_mail("example2.json")).toEqual(Array(10).fill({}));
        });
         it("Subject",
        function () {
            expect(ms.summarize_mail("example1.json",'Subject')).toEqual([{Subject: "[notmuch] archive"},
                                          {Subject: "Re: [notmuch] archive"},
                                          {Subject: "Re: [notmuch] archive"}]);
        });
         it("Subject, Date",
        function () {
            expect(ms.summarize_mail("example1.json",'Subject','Date')).toEqual(
            [{Subject: "[notmuch] archive", Date: 'Tue, 17 Nov 2009 18:21:38 -0500'},
             {Subject: "Re: [notmuch] archive", Date: 'Tue, 17 Nov 2009 18:04:31 -0800'},
             {Subject: "Re: [notmuch] archive", Date: 'Wed, 18 Nov 2009 02:22:12 -0800'}]);
        });
     });

Part 3: Objects and Constructors

Constructor

Referring to L11, create a 'Message' constructor that takes as input one of the objects returned by read_json_file and creates an object providing lower-cased a lower-cased accessor for the 'Subject', 'Date', 'From', and 'To' headers. Your constructor should pass pass the following tests; you should also add one or more extra tests to show that your Message class works with data read with read_json_file

let testMsg = new Message({'headers': {'Subject' : "lunch", 'Date' : "now"}});
describe("Message class",
         function() {
             it("new message is not null",
                function () {
                    expect(testMsg).not.toEqual(null);
                });
             it("subject accessor",
                function () {
                    expect(testMsg.subject).toEqual("lunch");
                });
         });

`equals` method

Write an equals method for your Message class. You may assume that each property of the Message object is a string or a number, but you should not hardcode the list of properties in your equals method (i.e. your equals method should continue to work if more string or number valued properties are added to the Message object).

Your method should pass at least the following tests:

let otherMsg = new Message({'headers': {'Subject' : "dinner", 'Date' : "now"}});
it("message is equal to itself",
   function () {
       expect(testMsg.equals(testMsg)).toEqual(true);
   });
it("message is not equal if field changes",
   function () {
       expect(testMsg.equals(otherMsg)).toEqual(false);
   });