Tag Archives: closures

Writing a jQuery plugin – (part 1). Good practices!

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JavaScript flexibility

In JS you have the natural flexibility to extend an object you have previously declared. Even more you can extend any native objects! That makes the writing of a jQuery, or whatever javascript library, plugins to be very easy.

As you may know in JS you can have object declared like that:

var obj = { a : 1, b : 2 };

That is an object with two properties a and b which values are respectively 1 and 2. If you’d like to extend this object later you can just write:

obj.c = 3

and now the object looks like that:

{ a : 1, b : 2, c : 3 }

That’s perfect when you’d like to write plugins to jQuery. Continue reading Writing a jQuery plugin – (part 1). Good practices! →

JavaScript closures in brief

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What’s a closure

Well every javascript programer knows that a variable defined in javascript file with the var declaration is global into all javascript code.

var a = 12;
console.log(a);

that code prints 12 into the console.

Note: console object is visible in Firefox and Safari, but not in IE, and here’s used just for the test!

Here comes the closures

Let’s assume I’ve two javascript files.

file1.js:

var a = 12;

file2.js:

a = 13;

Than obviously if I print out the variable a in file2.js after that line, I’ll have the value of a equal to 13, and this will be the value of the variable a from the file1.js, because that’s obviously the same variable. Continue reading JavaScript closures in brief →