WebFund 2016W Lecture 8

Video

The video from the lecture given on February 2, 2016 is now available.

What does the regular expression on line 92 of tinywebserver.js do? (Answer: Prevents breaking out of the current directory by using .. and ~)
What does path.normalize do? (Answer: Tries to fix a malformed path. e.g. /home//dave/ becomes /home/dave/)
What is Jade? (Answer: Templating language.)

One way to deal with potential errors is to surround code with a try/catch block
To further track down the problem, use the Node debugger
In class, there was a problem when reading/parsing the JSON option file
- Using the debugger, we saw that everything was fine parsing it
- The issue was that the errorpage did not exist from the working directory
- Make sure to have all the required files in the correct directory
- also, make sure you are working on the correct version of your code (in class, we were modifying the wrong code while debugging)

Jade is a templating language for HTML
HTML and Jade have a one-to-one correspondence (for the most part)
See: jade-lang.com for documentation
Jade is parsed on the server side, NOT the client side
In our example (form-demo), form data comes from the body (object) of the post request (object)
- The bodyparser is used to parse form data from the body of the request that has been received. The parsed data is then passed into a Jade template to be rendered along with the other Jade code into HTML

How does the extends keyword work in Jade?
- We write: extends JADE_FILE
- This allows a template to extend a parent template. It can then override fill in pre-defined blocks of content
- Jade supports template inheritance via the block and extends keywords. A block acts as a placeholder in the parent template which can be replaced in the child templates
- Allows for reuse of Jade templates

To render template with the Jade engine, we must tell the app to use the engine
- Specify that the app should use Jade: app.set('view engine', 'jade');
- Specify where to find the Jade templates: app.set('views', __dirname);
To render a Jade code, you can use jade.render('Jade code...', {/*Options go here*/})
- These options can be found on the documentation site: http://jade-lang.com/api/
To render a template, you can use jade.renderFile('Template', {/*Options go here*/})
To respond to a request with a rendered page, you can use res.render('Template', {/*Data to pass to the template goes here*/});
- Note, you don't specify a .jade extension
The render() method will convert the jade code or template to HTML

You can set what will be exported form a file using module.exports = SOME_OBJECT;
module.exports is the data "returned" by the file so that it can be used in other .js files
This is loaded using require(FILE)
- Note that this can only be used to load the same file once

Removing the line: app.use(bodyParser.urlencoded({extended:false}));
- The list page has no user people listed
- The form data wasn't parsed, so the page didn't have values to display
removing module.exports=router; from index.js:
- The following line in app.js will no longer have the expected return value to store in the routes variable: var routes = require('./routes/index');
- This means that none of the routing will work