js closure example

dfg.js

#!/usr/bin/env node

function celebrityIDCreator (theCelebrities) {
    var i;
    var uniqueID = 100;
        for (i = 0; i < theCelebrities.length; i++) {
            theCelebrities[i]["id"] = function (j)  {
                // the j parametric variable is the i passed in on invocation of this IIFE
                return function () {
                    return uniqueID + j;
                   /*each iteration of the for loop
                    * passes the current value of i
                    * into this IIFE and it saves
                    * the correct value to the array*/
                } () /*BY adding () at the end of this function,
               we are executing it immediately and returning
               just the value of uniqueID + j, instead of
               returning a function.*/
            } (i); // immediately invoke the function passing the i variable as a parameter
        }
    return theCelebrities;
}

var actionCelebs = [{name:"Stallone", id:0}, {name:"Cruise", id:0}, {name:"Willis", id:0}];

var createIdForActionCelebs = celebrityIDCreator (actionCelebs);

var stalloneID = createIdForActionCelebs [0];
console.log(stalloneID.id); // 100

var cruiseID = createIdForActionCelebs [1];
console.log(cruiseID.id); // 101

var willisID = createIdForActionCelebs [2];
console.log(willisID.id); // 102

console.log(createIdForActionCelebs);