| type | event description | target |
|---|---|---|
| load | Fires when HTML and all resources of a web page have finished loading | document, window |
| unload | Fires when web page is unloading for a new page requested | body, window |
| error | Fires when browser encounter a JS error or resource does not exist (inconsistent support) | |
| resize | Fires repeatedly as browser's window is being resized | window |
| scroll | Fires repeatedly as user scrolls web page | document, element |
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Usage:
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Window object that models
browser's windows and tabs.Document object that models
web pages displayed in browser's windows.The DOM API specification serves two purposes:
An HTML element consists of a tag and a set of attributes, an attribute being a pair name="value".
HTML Global attributes are attribute common to all HTML elements. They are divided in three subtypes: core attributes, event-handler attributes and xml attributes
Example: attributes of <body> element
See the Pen DOM tree: document.body.attributes by Massimiliano De Simone (@maxdesimone) on CodePen.
In the DOM an HTMLElement object represents an element of an HTML document. The attributes of an element become properties of the corresponding DOM HTMLElement object.
For example, you may set up google analytics for your web site, in that case you have to include in the home page a script like the one below, where you create a <script> element and then you set the attributes type, async and src using the dot notation.
<script>
var _ga = document.createElement('script');
_ga.type = 'text/javascript';
_ga.async = true;
_ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
<script>
An UML state machine diagram is used to show the behaviour of a system. In this case a state machine diagram demonstrates the behaviour of the document object that is its life cycle.
Earlier, we saw that regex engines support metacharacters \1, \2, \3, etc. to refer
to the text matched by parenthesized subexpressions.
Perl and most other modern regex-endowed languages also provide a way to refer to the text matched
by parenthesized subexpressions from code outside of the regular expression, after a match has been successfully
completed.
"A regular expression is a pattern which specifies a set of strings of characters; it is said to match certain strings."[Ken Thompson]
From the English dictionary:
A regex can or cannot match a string and, if it does, can match the string once or multiple times.
<script> element with src attribute.
<script> element is synchronous by default<script> element allow you to insert javascript in a HTML document.<script src="scripts/javascript_app.js"> </script> <!--synchronous script-->
When JavaScript engines encounters a <script> element, they stop parsing HTML to download and interpreter the JS file, then they resume parsing and rendering HTML.
The <script> element has two important attribute: HTML 4.1 defines the async attribute and HTML5 introduces the defer attribute. These two attributes cause scripts to be executed differently, in browsers supporting them.
| body | p | h3 | h2 | h1 | |
|---|---|---|---|---|---|
| pixel | 12px | - | 14px | 18px | 24px |
| percentage | 75% | - | 117% | 150% | 200% |
| em | 100% | 0.75em | 1.17em | 1.3em | 1.5em |
| body | p | h3 | h2 | h1 | |
|---|---|---|---|---|---|
| pixel | 16px | - | 18px | 24px | 32px |
| percentage | 100% | - | 133% | 150% | 200% |
| em | 100% | 1em | 1.125em | 1.5em | 2em |