LeeCroft at 15:29, 10 February 2016

2016-02-10T15:29:35Z

← Older revision		Revision as of 15:29, 10 February 2016
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	The video from the lecture given on February 9, 2016 [http://homeostasis.scs.carleton.ca/~soma/webfund-2016w/lectures/comp2406-2016w-lec10-09Feb2016.mp4 is now available].		The video from the lecture given on February 9, 2016 [http://homeostasis.scs.carleton.ca/~soma/webfund-2016w/lectures/comp2406-2016w-lec10-09Feb2016.mp4 is now available].

			==Student Notes==

			===Assignment 3 Solutions===

			*Solutions to the assignment questions have been posted on the [assignment 3 page http://homeostasis.scs.carleton.ca/wiki/index.php/WebFund_2016W:_Assignment_3]
			*Below is a review of these solutions

			====Q1====
			*What is the type of:
			**<code>line</code>: lines may be classified as an object but more specifically it is an array
			**<code>rawContents</code>: rawContents is of type string
			**<code>split()</code>: is a function. It is also acceptable to say that it is a method

			====Q2====
			*Line 24 should be printed first
			*Since JavaScript is single threaded there is a high guarantee it is printed first since the program runs asynchronously
			*In general, you can consider the program to do all of its main sequential work first and to then check for callback functions from asynchronous calls that must be run

			====Q3====
			*A one line change would be adding a line at line 42 by setting <code>status = 404;</code>
			*We can also change the docroot but it's an unsafe way

			====Q4====
			*Just before line 92 we can add another if statement
			*We check to see if the user-agent headers exists and whether it contains iPhone as a substring
			**If the condition is met, we respond with 403

			====Q5====
			=====A=====
			*By commenting out this line, <code>app</code> will no longer be defined
			*Anything referencing app will produce a reference error so the program crashes on the first line that uses app

			======Important Point======
			*What is the difference between JavaScript's <code>require</code> and C's <code>include</code>?
			**In C <code>include</code> looks similar to a <code>require</code> but in reality it’s a very different mechanism.
			**The <code>include</code> in C pre-processes the included file to put all of its code into the file that included it
			***Symbols are thus defined for us but there is no visible code! We cant tell what kind of symbols include has brought in
			**In JavaScript the file we require is pure JavaScript code!
			***The required script will run and put some value into its module.exports which is then returned via the require call
			***We know what symbol we are working with because we assign the return value of the require call ourselves

			=====B=====
			*Setting var port = 3000;
			*It works perfectly fine but we can no longer change the port using the PORT environment variable

			=====C=====
			*Since we change the directory, it can no longer find “views”
			*This means that the server will not be able to find any templates to render

			=====D=====
			*Commenting out line 24
			*We are no longer exporting anything from the file
			*Any calls to require the file will not get an expected return value from the require call and so the server will not work properly

			=====E=====
			*This line acts as a placeholder for child templates to put content into the body of this template
			*By removing it, the child templates have nowhere to put the content in the body

			=====F=====
			*When we indent the code in this way, the submit button is no longer a part of the form
			*The button will therefore not cause the form to be submitted
			*Essentially, the button no longer does anything


			===Possible questions for the Midterm===

			*What is the purpose of app.post? What if <code>app.post(‘/add’, ...)</code> were be changed to <code>app.get('/add', ...)</code>?
			**Answer: The server will no longer know how to deal with any incoming POST requests for /add so it will not properly handle the form submission
			***Instead, the server could handle an incoming GET request for the form submission (but there are some other problems that would need to be fixed for parsing the incoming data)
			*How can we keep it a get and still make it work?
			**Answer: Change the method in the form from method “post” to “get”
			***POST requests have the form data in their body whereas a GET request stores it in a query strings
			***So we can change <code>req.body</code> to <code>req.query</code> in the routing function to access the data properly

			<br>

			*What is <code>app.use()</code>?
			**What happens when we comment out the line <code>app.use( ‘logger'..)</code>?
			***The server no longer logs incoming request to the console
			**What if we comment out <code>app.use(body.parser...)</code>?
			***The program would crash because it wouldn’t be able to find <code>req.body</code> since the body of the request has no been parsed
			**What is the purpose of <code>app.use(express.static...)</code>?
			***Its tells the server to use a static web server to serve basic webpages and other static resources
			*So <code>app.use()</code> is telling the server to use a given module to do something with the incoming requests

Soma: Created page with "==Video== The video from the lecture given on February 9, 2016 [http://homeostasis.scs.carleton.ca/~soma/webfund-2016w/lectures/comp2406-2016w-lec10-09Feb2016.mp4 is now avai..."

2016-02-10T01:28:24Z

Created page with "==Video== The video from the lecture given on February 9, 2016 [http://homeostasis.scs.carleton.ca/~soma/webfund-2016w/lectures/comp2406-2016w-lec10-09Feb2016.mp4 is now avai..."

New page

==Video==

The video from the lecture given on February 9, 2016 [http://homeostasis.scs.carleton.ca/~soma/webfund-2016w/lectures/comp2406-2016w-lec10-09Feb2016.mp4 is now available].

WebFund 2016W Lecture 10 - Revision history

LeeCroft at 15:29, 10 February 2016

Soma: Created page with "==Video== The video from the lecture given on February 9, 2016 [http://homeostasis.scs.carleton.ca/~soma/webfund-2016w/lectures/comp2406-2016w-lec10-09Feb2016.mp4 is now avai..."