Node’s Reference to Files

  node.js, question

File app.js:

var c1 = require('./c1');
 
 var cc = new c1;
 c1.f11();

File c1.js:

function f1(a, b){
 this.f11 = function(c, d){
 console.log(c);
 bracket
 bracket
 
 module.exports = f1;

node app.jsShow laterc1.f11 is not a function, Why?

Is the meaning of the code here different from that of the following code?

function f1(a,b){
 this.f11 = function(c,d){
 alert(c);
 bracket
 bracket
 
 var vv = new f1;
 vv.f11(2, 3);

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