JavaScript Details

JavaScript is one three languages used for web development:

HTML defines the content of web pages
CSS specifies the layout of web pages
JavaScript programs the behavior of web pages

"JavaScript is the only programming language people attempt to use before they know anything about it".

Douglas Crockford, JavaScript: The Good Parts

In C-like languages, the semicolon denotes the end of a statement. Unlike other C-like languages, JavaScript does not always enforce the use of a semicolon at the end of a statement. Rather, a carriage return may be "understood" as a missing semicolon, resulting in different semantics.

In JavaScript, a semicolon is automatically inserted when

two statements are separated by a line terminator
two statements are separated by a closing brace }
a line terminator follows a break, continue, return, or throw.

Some libraries have evolved to simplify using JavaScript. This allows those who don't know all the details of the language to use it in a masterful way. JQuery and Bootstrap make your life easier.

What can you do with JavaScript

Select nodes by tag, id or class
Determine if a document has finished loading
Change the web page after it has loaded
Validate user-entered text before it returns to the server
Create functions that run on the client (in the browser)

JavaScript Details