Custom Module Export

/**Custom Module Export */

/* Lets see how to export your own module so that it could be read by other Js program */

/* actually a module can be exported in two ways:

1) using :

exports.custObj = 123;

2) using :

module.exports = 123;

says we have created a new file CustomModule.js and put the below line:

exorts.custObj = 123;

and we can get this exported value in other program say, UseExported.js:

var expVal = require("./CustomModule");

console.log(expVal);//will print { custObj: 123 }

but if we have exported the value by directly assigning to exports object like:

exports = 123;

and imported it in other js file

var expVal = require("./CustomModule");

console.log(expVal);//will print {} ,an empty object why??

Heres how, actually the CustomModule file have an internal module object which is like:

var module = {

exports : {}

};

and it provide short form of using :

var exports = module.exports;//pointing to {}

and when CustomModule code will return the internal code returns module.exports object

thus if someone ovveride like exports = 123, then what happen is like below

exports = 123;//user wants to export this value

then when custome module program actually return will call internally "return module.exports" which is still pointing to {}

thus if user uses this export in other program

it will simply print {} (becuase the short form var exports = module.exports points to the object and we ovveride it

not the object)

now lets do it by module.exports by assigning value to it:

module.exports = 123;//user want to export this constatnt value

,but when program return it will internally "return module.export;" ,which were pointing to {}

but you override the module.eports itself to 123, thus it will be the final value that will be exported i.e, 123

thus

var expVal = require("./CustomModule");

console.log(expVal);//will print 123

thus remeber when a custom module return ,it calls at the end "return module.exports;"

if you override module.exports , you are ovveriding the actual object.

if you do module.exports.custObj = 123;//it will be {custObj : 123}, becuase module.exports point to {}

and module.exports.custObj is like creating a property in object {}.

like wise if we do exports.custObj = 123; //which internally likes module.exports.custObj = 123

thus when module code returns it call "return module.exports;"//{custObj : 123}

and can be accessed:

console.log(expVal);//will print {custObj : 123}

console.log(expVal.custObj);//will print 123

Also note:

You have created a Custome module, but you have not done any assignment to exports or module.exports.

Even on this also, if someone require you module it will give {}, thus it proves that require function call

will look for the module.exports if not the default one {} will be taken.

*/