es6 closures

1function makeAdder(x) {
2  return function(y) {
3    return x + y;
4  };
5}
6
7var add5 = makeAdder(5);
8var add10 = makeAdder(10);
9
10console.log(add5(2));  // 7
11console.log(add10(2)); // 12

1var makeCounter = function() {
2  var privateCounter = 0;
3  function changeBy(val) {
4    privateCounter += val;
5  }
6  return {
7    increment: function() {
8      changeBy(1);
9    },
10    decrement: function() {
11      changeBy(-1);
12    },
13    value: function() {
14      return privateCounter;
15    }
16  }
17};
18
19var counter1 = makeCounter();
20var counter2 = makeCounter();
21alert(counter1.value()); /* Alerts 0 */
22counter1.increment();
23counter1.increment();
24alert(counter1.value()); /* Alerts 2 */
25counter1.decrement();
26alert(counter1.value()); /* Alerts 1 */
27alert(counter2.value()); /* Alerts 0 */
28

1function OuterFunction() {
2
3    var outerVariable = 100;
4
5    function InnerFunction() {
6        alert(outerVariable);
7    }
8
9    return InnerFunction;
10}
11var innerFunc = OuterFunction();
12
13innerFunc(); // 100
14