Let’s assume there’s a little, simple JavaScript array:
var a = [3,2,4,5,2,4,5,8]; |
If you pop() an element from it – what element will be taken? The answer is a bit frustrating, but logical – the last one:
var b = a.pop(); alert(b); // this will result in 8 |
Continuing from my post about PHP arrays coding style and following the comments of that post, I’d like to write a bit about JavaScript objects’ coding style.
You perhaps know that the term object is quite undefined or under estimated in the JavaScript world, but I’d speak about the key/value pairs in JS commonly formatted like that:
var obj = { key : 'value' } |
Here you can add more and more key/value pairs, but what’s different from the PHP associative arrays and what’s the same and should be cosidered.
I wrote about the alignment in PHP and hashes. Than I showed how I align them:
$arr = array( 'short' => 'val', 'longkey' => 'val' ); |
In JavaScript you should use the same technique of alignment:
var obj = { 'short' : 'val', 'longkey' : 'val' }; |
Yes, there are more differences, which is normal. First of all you don’t have the => notation in JavaScript and a : is used. Second and most important you cannot add a trailing comma after the last key/value pair. Note that in PHP that’s fine!
// that will throw an error in MSIE var obj = { 'short' : 'val', 'longkey' : 'val', }; |
while this is OK in PHP and it’s encouraged:
$arr = array( 'short' => 'val', 'longkey' => 'val', ); |
As most of the desktop software gives us opportunity to choose from typical or custom installations, let me write what’s a typical IF conditional statement in JavaScript and … every other programing language.
if ( thisIsTrue ) { printMe("some message"); } |
The first thing you can improve from the code above is removing the brackets.
if ( thisIsTrue ) printMe("someMessage"); |
Because in JavaScript everything’s on the client – every symbol matters. What if we remove as much as we can!
thisIsTrue && printMe("someMessage"); |
Almost for everybody the JavaScript way of implementing inheritance is odd. For a typical programmer it should look more C or Java like, but is not. However to give you a breve example, I’d like to make two objects, and to make the second one to inherit from the first. Thus I’d like to show how neither parent or child objects interact once they have been instanciated.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 | var parent = function() {}; parent.prototype = { name : 'parent', m : 1, a : function() { console.log(this.name + ': ' + this.m); }, setM : function( value ) { this.m = value; } }; var child = function() {}; child.prototype = new parent; child.prototype.name = 'child'; var parentObj = new parent(); var childObj = new child(); parentObj.a(); parentObj.setM(12); childObj.a(); childObj.setM(3); parentObj.a(); childObj.a(); |
However this describes the ability to make complex JavaScript inheritance patterns. The complete source’s here.
In fact every normal developer will try to make his code as readable as possible. In a normal world a JavaScript IF statement will look like so:
if ( expression ) myFunc();
where expression is something that can be either true or false and myFunc is just an example what can be called if the expression is true.
Yes, and just because is JavaScript every single character is important. Actually you can convert the row above with that one bellow:
expression && myFunc()
Than if expression is faulty myFunc() will not be called. That is really extreme and in the same time is quite clear to read.