WebFund 2014W Lecture 4
The audio from the lecture given on January 17, 2014 is available here.
Assignment 1 Discussion
• Pieces of the code
o Node o Jade o HTTP o Bootstrap o jQuery o HTML
• How do the other pieces fit?
o Look at the top, at the require lines o Reference to the node's module system Searches for the directory indicated for an index.js file All loaded into variable you loaded it into (an 'exports' object is returned) Methods in the index.js beginning with "exports" are accessible by the var you loaded the object into
• When does app.js end?
o In the fraction of the second of when it's called o Purpose of the file is to set up the page o app.get and app.post Registered as callbacks since they run once and never again, but the functions that are registered ran everytime it's requested for app.get: if one parameter, you're accessing a field; 2 parameters and you're specifying a path o app.use calls specific code from the parameter indicated path: directory name express.static
• apache; a static webserver; anything in the directory indicated can be accessed
o app.set sets a field in the app object specified in the first parameter, to whatever specified in the second parameter o Ordering of lines in app.js is important e.g. having something loaded before loading the public folder's files tells node that the previous file takes precedence
• When rendering an object (res.render) for a response to a request, you pass in a jade template, and an object with fields (parameterizing the template) • View engine: engine used as a template for HTMLs (e.g. 'jade')
o completely restricted access to server objects/variables due to security concerns; templates are isolated o since we want to dynamically generate the page, we have to use a template o some things we want to keep constant and not have to rerender all the time, and sometimes we want to change specific content o makes it clear that we're not writing HTML, just a template that will be converted into an HTML document
• Spaces and tabs do not mix in jade. Use one only. • Why do we need a different language for Jade?
o Domain-specific languages In Computer Science, a way to solve a problem is to create a language to solve it Makes things, previously complicated, easy CSS does not look like HTML, because it is a domain-specific language Compound languages: always language embedding
o Built off jQuery o Runs on the client; completely in the browser allows you to dynamically change CSS to fit user's browser/screen (i.e. on the phone), less intensive on you (offloading a lot of work onto the browser) Major Reason: latency
• Everytime you make a request, to the server, it takes time an incredibly short time • Annoying for the user to constantly wait for pages/response to actions • Downloads webpages in the background; predicting what you will need soon in order to save time