WebFund 2016W Lecture 2 - Revision history

LeeCroft at 15:36, 22 January 2016

2016-01-22T15:36:47Z

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	* JavaScript has '''nothing''' to do with Java.		* JavaScript has '''nothing''' to do with Java.
	** Why is it even called JavaScript then? At first it wasn't; it was developed as Mocha, changed to LiveScript and then finally renamed to JavaScript due to an agreement with Sun (acquired by Oracle).<ref>[http://stackoverflow.com/a/2475528]</ref>		** Why is it even called JavaScript then? At first it wasn't; it was developed as Mocha, changed to LiveScript and then finally renamed to JavaScript due to an agreement with Sun (acquired by Oracle).<ref>[http://stackoverflow.com/a/2475528 Stack Overflow - Why is JavaScript called JavaScript, since it has nothing to do with Java?]</ref>
	* The only similarity between Java/JavaScript is some of the syntax, but that can be said for a lot of languages.		* The only similarity between Java/JavaScript is some of the syntax, but that can be said for a lot of languages.

	* What's different about JavaScript?		* What's different about JavaScript?
	** No declared data types; it's a ~~"loose"~~ language.		** No declared data types; it's a loosely typed language.
	*** Instead of int i = 0, it's simply var i = 0.		*** Instead of int i = 0, it's simply var i = 0.
	** There's seven data types<ref>[https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures]</ref> (examples in brackets)		** There's seven data types<ref>[https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures MDN - JavaScript Data Structures]</ref> (examples in brackets)
	*** Boolean (true, false)		*** Boolean (true, false)
	*** Number (3.1337, 1337, etc. There's no integer or long, everything is a float)		*** Number (3.1337, 1337, etc. There's no integer or long, everything is a float)
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	If you've previously worked with Java, the first large difference you've noticed is likely that variables are very "flexible".		If you've previously worked with Java, the first large difference you've noticed is likely that variables are very "flexible".

	* ~~If you attempt~~ to use a variable that has not been declared~~, you~~ will ~~'''not''' get~~ a ~~compiler~~ error~~. Instead,~~ the ~~type~~ <tt>undefined</tt> ~~will be returned. This can making debugging a bit of a challenge!~~		* Trying to use things that have not been declared can produce some behaviour that you might not expect:
	* ~~Likewise with most~~ languages, a symbol ~~(e.g., <tt>~~x~~</tt>)~~ can ~~only reference ''one''~~ object (which can ~~optionally~~ encapsulate other ~~objects).~~		** Referencing a variable that has not been declared will produce a reference error
	* You can ~~have several~~ types of data ~~inside single object~~ (e.g., <tt>x.y</tt>, <tt>x.y.z</tt>, <tt>x.y.x.qwerty</tt>, etc).		** Assigning a value to a variable that has not been declared will implicitly declare the variable at the global level (avoid doing this by explicitly declaring your variables)
			** Accessing a property that does not exist in an object will give you <code>undefined</code>
			* Similar to how in other languages, a symbol x can refer to an object which can encapsulate other object or types of data, in JavaScript, an object can hold various types of data in its properties (e.g., <tt>x.y</tt>, <tt>x.y.z</tt>, <tt>x.y.x.qwerty</tt>, etc).
	* <tt>x.size</tt> (dot notation) is the same as <tt>x["size"]</tt> (array notation).		* <tt>x.size</tt> (dot notation) is the same as <tt>x["size"]</tt> (array notation).
			* Functions are also a special type of object and they can be stored in a variable.
	* JavaScript engines use a garbage collector, so you do not need to manually deallocate memory (in C you need to). Unlike Java, you can "reuse" a variable name and use a completely different type; e.g. creating <tt>var x = 1337</tt> and then <tt>x = "Dave"</tt> later is completely valid.		* JavaScript engines use a garbage collector, so you do not need to manually deallocate memory (in C you need to). Unlike Java, you can "reuse" a variable name and use a completely different type; e.g. creating <tt>var x = 1337</tt> and then <tt>x = "Dave"</tt> later is completely valid.

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	To open up Read-Eval-Print-Loop (REPL), run <tt>node</tt> in a terminal. For more details on setting your environment up, see [[WebFund_2016W:_Tutorial_1#Running_the_VM\|Tutorial 1]].		To open up Read-Eval-Print-Loop (REPL), run <tt>node</tt> in a terminal. For more details on setting your environment up, see [[WebFund_2016W:_Tutorial_1#Running_the_VM\|Tutorial 1]].

	==References==		====References====
	~~{{Reflist}}~~		<references/>

Zero: New section added.

2016-01-18T18:34:01Z

New section added.

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	https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions		https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions

			====Synchronous vs. Asynchronous====

			* Synchronous (blocking) functions are where a task must be fully complete before the next task can be begin.
			** Examples:
			*** Waiting on a single network connection before accepting additions requests.
			*** Waiting for a file to be fully loaded before displaying it in a text editor.
			* Asynchronous (non-blocking) functions are where the program is allowed to continue with other tasks while another one is in process.
			** Examples:
			*** Accepting new network connections while another connection is already in progress.

	====Node.js====		====Node.js====

Zero: /* Student Notes */

2016-01-18T18:22:30Z

Student Notes

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	=====Getting started with Node.js=====		=====Getting started with Node.js=====

	To open up Read-Eval-Print-Loop (REPL), run <tt>node</tt> in a terminal. For more details on setting your environment up, see [[WebFund_2016W:_Tutorial_1#Running_the_VM\|Tutorial 1]]		To open up Read-Eval-Print-Loop (REPL), run <tt>node</tt> in a terminal. For more details on setting your environment up, see [[WebFund_2016W:_Tutorial_1#Running_the_VM\|Tutorial 1]].

	==References==		==References==
	{{Reflist}}		{{Reflist}}

Zero: /* Node.js */

2016-01-18T18:20:52Z

Node.js

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	* Has specialized libraries for networking, file system access, etc that you usually wouldn't find in a browser (mostly for security reasons). These functions have their own set of [https://nodejs.org/api/ documentation].		* Has specialized libraries for networking, file system access, etc that you usually wouldn't find in a browser (mostly for security reasons). These functions have their own set of [https://nodejs.org/api/ documentation].
	* Has no default graphic frontend such as WebKit (although there are libraries to provide that if you wish).		* Has no default graphic frontend such as WebKit (although there are libraries to provide that if you wish).

			=====Why use Node.js?=====

			* JavaScript makes it easier to write asynchronous functions.
			* You can reuse your knowledge on client-side JavaScript to apply to server-side Node.js applications.

	=====Getting started with Node.js=====		=====Getting started with Node.js=====

Zero: /* How should I learn JavaScript? */

2016-01-18T18:15:50Z

How should I learn JavaScript?

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	** [https://www.codecademy.com/learn/javascript Codecademy] has a lot of good resources for beginners.		** [https://www.codecademy.com/learn/javascript Codecademy] has a lot of good resources for beginners.
	** For more advanced students, check on [https://github.com/search?l=javascript&o=desc&q=stars%3A%3E1&s=stars&type=Repositories GitHub] to see if there's any projects you're interested in contributing to. If you plan to work in web development, it's very likely you will be asked in an interview if you've contributed to any open source projects (having a good portfolio will help a ''lot'' in getting a first job).		** For more advanced students, check on [https://github.com/search?l=javascript&o=desc&q=stars%3A%3E1&s=stars&type=Repositories GitHub] to see if there's any projects you're interested in contributing to. If you plan to work in web development, it's very likely you will be asked in an interview if you've contributed to any open source projects (having a good portfolio will help a ''lot'' in getting a first job).
			* The Mozilla Developer Network maintains a [https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference JavaScript reference] that is recommend. ''(Note: There is no official documentation for Google Chrome's V8 engine, although there is an [http://v8.paulfryzel.com/docs/master/index.html unofficial reference].)''

	====Working with Variables====		====Working with Variables====

Zero: /* Node.js */

2016-01-18T18:10:25Z

Node.js

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	* Contains a package manager called npm to manage dependencies (libraries).		* Contains a package manager called npm to manage dependencies (libraries).
	* Has specialized libraries for networking, file system access, etc that you usually wouldn't find in a browser (mostly for security reasons).		* Has specialized libraries for networking, file system access, etc that you usually wouldn't find in a browser (mostly for security reasons). These functions have their own set of [https://nodejs.org/api/ documentation].
	* Has no default graphic frontend such as WebKit (although there are libraries to provide that if you wish).		* Has no default graphic frontend such as WebKit (although there are libraries to provide that if you wish).

Zero: /* Working with Variables */

2016-01-18T18:07:56Z

Working with Variables

← Older revision		Revision as of 18:07, 18 January 2016
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	* If you attempt to use a variable that has not been declared, you will '''not''' get a compiler error. Instead, the type <tt>undefined</tt> will be returned. This can making debugging a bit of a challenge!		* If you attempt to use a variable that has not been declared, you will '''not''' get a compiler error. Instead, the type <tt>undefined</tt> will be returned. This can making debugging a bit of a challenge!
	* Likewise with most languages, a symbol (e.g., <tt>x</tt>) can only reference ''one'' object.		* Likewise with most languages, a symbol (e.g., <tt>x</tt>) can only reference ''one'' object (which can optionally encapsulate other objects).
	* You can have several types of data inside single object (e.g., <tt>x.y</tt>, <tt>x.y.z</tt>, <tt>x.y.x.qwerty</tt>, etc).		* You can have several types of data inside single object (e.g., <tt>x.y</tt>, <tt>x.y.z</tt>, <tt>x.y.x.qwerty</tt>, etc).
	* <tt>x.size</tt> (dot notation) is the same as <tt>x["size"]</tt> (array notation).		* <tt>x.size</tt> (dot notation) is the same as <tt>x["size"]</tt> (array notation).

Zero: Typo. Thanks Lee.

2016-01-15T03:16:50Z

Typo. Thanks Lee.

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	====Node.js====		====Node.js====

	Node.js is designed to provide a server side environment of JavaScript. Instead of using Google's V8 JavaScript inside Chrome/Chromium, Node.js uses the V8 engine directly. Because Node.js is meant to be used outside of the browser, there's some ~~slightly~~ differences.		Node.js is designed to provide a server side environment of JavaScript. Instead of using Google's V8 JavaScript inside Chrome/Chromium, Node.js uses the V8 engine directly. Because Node.js is meant to be used outside of the browser, there's some slight differences.

	* Contains a package manager called npm to manage dependencies (libraries).		* Contains a package manager called npm to manage dependencies (libraries).

Zero: Added bit about garbage collectors.

2016-01-14T15:50:44Z

Added bit about garbage collectors.

← Older revision		Revision as of 15:50, 14 January 2016
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	* You can have several types of data inside single object (e.g., <tt>x.y</tt>, <tt>x.y.z</tt>, <tt>x.y.x.qwerty</tt>, etc).		* You can have several types of data inside single object (e.g., <tt>x.y</tt>, <tt>x.y.z</tt>, <tt>x.y.x.qwerty</tt>, etc).
	* <tt>x.size</tt> (dot notation) is the same as <tt>x["size"]</tt> (array notation).		* <tt>x.size</tt> (dot notation) is the same as <tt>x["size"]</tt> (array notation).
			* JavaScript engines use a garbage collector, so you do not need to manually deallocate memory (in C you need to). Unlike Java, you can "reuse" a variable name and use a completely different type; e.g. creating <tt>var x = 1337</tt> and then <tt>x = "Dave"</tt> later is completely valid.

	====Regular Expressions (Regex)====		====Regular Expressions (Regex)====

Zero: Typo fix.

2016-01-14T15:46:03Z

Typo fix.

← Older revision		Revision as of 15:46, 14 January 2016
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	* Practice! While attending the lectures is a great start, you ''will'' have to practice outside of class. This will not be graded, but will ultimately affect your performance in the course (and in the workplace).		* Practice! While attending the lectures is a great start, you ''will'' have to practice outside of class. This will not be graded, but will ultimately affect your performance in the course (and in the workplace).
	** [https://www.codecademy.com/learn/javascript Codecademy] has a lot of good resources for beginners.		** [https://www.codecademy.com/learn/javascript Codecademy] has a lot of good resources for beginners.
	** For more advanced students, check on [https://github.com/search?l=javascript&o=desc&q=stars%3A%3E1&s=stars&type=Repositories GitHub] to see if there's any projects you're interested in ~~contribution~~ to. If you plan to work in web development, it's very likely you will be asked in an interview if you've contributed to any open source projects (having a good portfolio will help a ''lot'' in getting a first job).		** For more advanced students, check on [https://github.com/search?l=javascript&o=desc&q=stars%3A%3E1&s=stars&type=Repositories GitHub] to see if there's any projects you're interested in contributing to. If you plan to work in web development, it's very likely you will be asked in an interview if you've contributed to any open source projects (having a good portfolio will help a ''lot'' in getting a first job).

	====Working with Variables====		====Working with Variables====