From MapbenderWiki

Contents 1 Variable names 1.1 Layout 1.2 Good names 1.2.1 boolean variables 2 Arrays 3 Scope 4 General advice

Variable names

Layout

• first letter lowercase, first letter of each following word uppercase, underscore is forbidden

var goodLayoutButCrappyName;  //Javascript
$goodLayoutButCrappyName;     //PHP

• if the variable name contains an acronym like WMS, only write the first letter of the acronym in uppercase

var myWMSDocument; // bad JS
var myWmsDocument; // good JS

• constants: uppercase, all caps with underscores

const NUMBER_OF_PAGES = 100     //Javascript
define("NUMBER_OF_PAGES", 100); //PHP

Good names

• has to describe the represented entity accurately
• as specific as possible

bad

temp = ... 
x = ...

good

scaleFactor = ...

• problem-oriented (printerReady instead of bitFlag)
• average length: 10 to 20 characters
• put modifier at the end of the name (Max, Average, String etc)
• avoid ambiguities (f.e. numSales refers to a total, salesNum to an index...avoid num if possible)
• i, j, k are integer indices only
• avoid abbreviations at all or include them in the code conventions
• avoid similar names in the same piece of code (like input and inputValue)
• avoid numerals in names (like value1 and value2)
• avoid words that are commonly misspelled (calender and calendar, or receive and recieve)
• avoid multiple natural languages (f.e. english only)
• avoid names of standard types, variables, routines (like then = 1)
• avoid names with hard to read characters (like chartI and chartl)

boolean variables

• names that imply true or false
• suffix like done, error, found, success
• prefix "is" is an option (like isPrinterReady)
• use positive names to avoid double negations (f.e. if (! notFound))

Arrays

• if an array can be replaced by a stack, use stack syntax like push and pop to avoid index trouble

bad

$someArray[count($someArray)-1] = $someValue; //PHP
someArray[someArray.length-1] = someValue     //JavaScript

good

array_push($someArray, $someValue); //PHP
someArray.push(someValue);          //Javascript

reconsider in performance relevant scenarios...push and pop are slower.

• use shortcut for Array declarations

bad

var someArray = new Array() //Javascript

good

var someArray = []; //Javascript

Scope

• in PHP: redirect variables from $_GET, $_POST, $_SESSION at the top of your script. Avoid the use of import_request_variables!

Example:

$backlink = $_REQUEST["backlink"];
$wfs_conf_id = $_REQUEST["wfs_conf_id"];
$frame = $_REQUEST["frame"];
$filter = $_REQUEST["filter"];
$url = $_REQUEST["url"];

• keep variables alive for as short a time as possible
• begin with minimal scope and expand whenever necessary
• don't assign a value to a variable until just before the value is used
• maybe identify global variables (e.g. by prefix global_)

General advice

• good names avoid need for comments
• use each variable for exactly one purpose
• avoid variables with hidden meanings (like pageCount equals -1 in error case)
• avoid magic numbers, use constants instead (never write for (var i=0; i<99; i++))
• make type conversions obvious
• use booleans to document your program (f.e. by adding a variable that stores the result of a complex boolean expression)

Example:

var isGeomColumn = (parseInt(wfsConf[attr]['element'][elementIndex]['f_geom']) == 1); 

if (isGeomColumn) {
  ...
}

• use true and false (not 0 and 1)