ECMAScript Syntax

Document created by resplin Employee on Jun 6, 2015
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The official documentation is at: http://docs.alfresco.com



JavaScript API
Developers familiar with languages such as Java, C, and Perl will find ECMAScript syntax easy to
pick up because it borrows syntax from each. Java and ECMAScript have several key syntax features
in common, as well as some that are completely different.
The basic concepts of ECMAScript are the following:

Everything is case-sensitive. Just as with Java, variables, function names, operators, and
everything else is case-sensitive, meaning that a variable named test is different from
one named Test.

Variables are loosely typed. Unlike Java and C, variables in ECMAScript are not given a
specific type. Instead, each variable is defined using the var operator and can be initialized
with any value. This enables you to change the type of data a variable contains at any
point in time (although you should avoid doing so whenever possible). Some examples:

var color = 'red';
var num = 25;
var visible = true;


End-of-line semicolons are optional. Java, C, and Perl require that every line end with a semicolon
(;) to be syntactically correct; ECMAScript allows the developer to decide whether or not
to end a line with a semicolon. If the semicolon is not provided, ECMAScript considers the end
of the line as the end of the statement (similar to Visual Basic and VBScript), provided that this
doesn�t break the semantics of the code. Proper coding practice is to always include the semicolons
because some browsers won�t run properly without them, but according to the letter of
the ECMAScript standard, both of the following lines are proper syntax:

var test1 = 'red'
var test2 = 'blue';

Comments are the same as in Java, C, and Perl. ECMAScript borrowed its comments from
these languages. You can easily edit JavaScript by JavaScript editor. There are two types of comments: single-line and multiline. The single-line
comments begin with two forward-slashes (//), whereas multiline comments begin with a
forward-slash and asterisk (/*) and end with an asterisk followed by a forward-slash (*/).


 
      //this is a single-line comment
      /* this is a multiline
      comment */

Braces indicate code blocks. Another concept borrowed from Java is the code block. Code
blocks are used to indicate a series of statements that should be executed in sequence and are
indicated by enclosing the statements between an opening brace ({) and a closing brace (}).
For example:



if (test1 == 'red') {
  test1 = 'blue';
  alert(test1);
}

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