How JavaScript closure works

new_gist_file.js

//From http://stackoverflow.com/questions/111102/how-do-javascript-closures-work

function sayHello2(name) {
    var text = 'Hello ' + name; // Local variable
    var say = function() { console.log(text); }
    return say;
}
var say2 = sayHello2('Bob');
say2(); // logs "Hello Bob"

// The above code has a closure because the anonymous function function() { console.log(text); } 
// is declared inside another function, sayHello2() in this example. In JavaScript, if you use the 
// function keyword inside another function, you are creating a closure.

/* 
 * Whenever you use function inside another function, a closure is used.
 * Whenever you use eval() inside a function, a closure is used. The text you eval can reference local 
   variables of the function, and within eval you can even create new local variables by using eval('var foo = …')
 */