Access local variable from the global context?

Question

function wrapValue(n) {
  var localVariable = n;
  return function() { return localVariable; };
}

var wrap1 = wrapValue(1);
var wrap2 = wrapValue(2);
console.log(wrap1());
// → 1
console.log(wrap2());
// → 2

In this example how is it allowed to access localVariable, which is local to wrapValue() function, from the global environment?
The book, included this example, stated the reason as follows: "multiple instances of the variable can be alive at the same time".
But I didn't understand.

It's called a closure,.. https://developer.mozilla.org/en-US/docs/Web/JavaScript/Closures — Keith, Dec 19 '17 at 10:47
localvariable is a local variable, which will be created for each method invocation. You are exposing this variable using closure. — gvmani, Dec 19 '17 at 10:47
It's closures, JavaScript has access to all the variables in the parent scope.. — Mr. Alien, Dec 19 '17 at 10:47
The important thing is that `localVariable` is not local to the function (definition), but rather local to each *call* of `wrapValue()` — Bergi, Dec 19 '17 at 10:52

score 0 · Answer 1 · answered Dec 19 '17 at 10:50

0

Your function sets a private value (localVariable) when called and returns it immediately so you can assign it to a another variable without change the private var inside function.

answered Dec 19 '17 at 10:50

Mosè Raguzzini

15,399
1
31
43

Access local variable from the global context?

1 Answers1