Learn By Example: The Foundations of HTML, CSS & Javascript

The internet is all about links. Who links to you and who do you link to? In this lecture we'll learn how we link to others using the <a> tag and its href attribute.

Paths in HTML can reference resources on our server as well as resources anywhere on the web. Relative paths are relative to the location of the HTML file and absolute paths can access resources on any server.

Bulleted lists and numbered lists. HTML has special <ul> and <ol> tags to specify these. Each list item in an <li> tag should go with either an un-ordered list (<ul>) or an ordered list (<ol>).

The <em>, <time>, <strong> and <code> tags.

Understand the different parts of a domain name and what they represent. Revisit the <a> tag and learn some more about how we can open up a new web page in a new window, tab etc.

The <img> tag allows you to embed inline images in your page. You can also resize images using the height and width attribute of the <img> tag.

HTML is a living standard now. No more version numbers and everything will be backward compatible from here on in. This is a pretty big deal!

Get re-introduced to CSS and see how CSS files are set up separately from the HTML and linked to the HTML page. It's good practice to separate the CSS and HTML files so both can be worked on separately.

How do you apply styles to specific HTML elements? You select them. How do you select them? By specifying the tag, a CSS class or their unique identifier.

Understanding sans-serif fonts, fallback options on a webpage, using fonts from free services such as Google etc.

How to change text color, background colors and specify colors using their hex code.

Understand margins, padding and borders and where exactly they apply. They form the CSS box model which has tripped up many an aspiring web developer.

Figure out why the "cascade" exists in Cascading Stylesheets.

The <span> allows logical grouping of inline elements and is a perfect partner to <div>.

The CSS float and clear properties.

Understand the CSS position attribute and how it works.

Fluid layouts allow the elements of a page to move as the page resizes, but you might not want them to! Then you'd choose the fixed layout.

The display property can make block elements behave like inline elements, make elements disappear and whole bunch of other stuff.

A simple Javascript example explained, take in user input and display it to the user in a pop up window.

Chrome developer tools offers a very cool way to print out statements on the developer console. Use this to see the result of your JS code.

Javascript variables can be local to a scope or global to the entire program.

If you leave out the var keyword the variable is undeclared and undeclared variables default to global. Always declare your JS variables.

A local variable takes precedence over a global variable of the same name.

Javascript variables hold their value only as long as the current page is loaded. A page refresh re-initializes all global variables.

Shallow copies and deep copies of an array, what they mean and how they work.

Use array.push() to append new elements to the end of an array.

Use array.splice() to remove elements from an array.

Javascript is not strongly typed, which means you can mix and match elements of different types in the same array.

Accessing non-existent elements in arrays is not an error in Javascript. It simply returns undefined.

JSON can be used as a textual representation of a JS object. You can construct an object using JSON notation.

Object constructors are just functions with two specific differences. The use of the magical keyword "this" within the constructor and the use of the magical keyword "new" to create an object from the constructor

You can add properties to an object after it's been constructed on the fly! Pretty mind-bending for programmers from other object oriented languages.

You can also remove properties from objects after they have been constructed. Again not allowed in traditional object oriented languages!

Functions are first class citizens in Javascript which means that object properties can be function as well.

Object properties defined in constructors can be functions as well! Again because functions are first class citizens.

A special for loop exists to loop over object properties. Every object supports this thanks to the base Object class!

Bad things happen when you call an object constructor without the new keyword.

The typeof operator tells you whether a variable is a number, string, object or undefined. It cannot differentiate between different types of objects though.

Use the instanceof operator to figure out what constructor was used to create an object. This only recognizes where the object came from, it does not know what changes were made to the object after it was constructed.

Properties are public by default, however it's often useful to have private properties. These are not natively supported in JS but we can fake them.

First class functions mean that we can pass them as arguments to functions.

Arrays and objects are pass by reference, this means that modifications within functions are reflected in the calling code. But not reassignments! What's the difference? This lecture explains it all.

Null unlike undefined is a special value with a type object.

This weird JS quirk causes many headaches, if it's NaN it's not a number.

The == causes conversions between numbers and strings with strange results. These can trip up even the most experienced programmer.

The == is the quality operator and === is the strict equality operator. Knowing the difference can save you trouble down the road.

Cute names to describe strings or numbers which are evaluated to true or false using the equality (==) operator.

Strings are actually objects and are immutable. What does that mean? This lecture explains it all.

Two types of function declarations in JS, declared functions and function literals. The names are intimidating but the concepts simple. They behave the same way except for one teeny tiny thing.

Nested functions need not only be function literals, they can be declared as well.

Closure variables have precedence over local as well as global variables. You can't control the value of a variable that a nested functions sees!

The function parameters of the outer function also form part of the referencing environment in the closure.

An object's prototype can change on the fly - this is called Dynamic Prototyping, and this can lead to some pretty surprising effects in Javascript

A chain of inheritance can be implemented via prototypes - the Javascript interpreter will walk up the hierarchy until it can resolve a property.

You can use the prototype keyword to override a property of all objects! Its a lot more powerful than simply overriding a property on a single object.

Javascript has a prototype Object, from which all objects derive. In this sense its exactly like Java (of course the mechanism of inheritance is very different in Javascript)

Did you know that its possible to override properties even of built-in object types, such as strings? Do so with care!