js-runtime-augmented-scope.js

/**
 * JavaScript runtime-augmented scope example.
 */

let x = 10;

let o = {x: 30};
let storage = {};

(function foo(flag) {

  if (flag == 2) {
    eval("var x = 20;");
  }

  if (flag == 3) {
    storage = o;
  }

  with (storage) {

    // "x" may be resolved either
    // in the global scope - 10, or
    // in the local scope of a function - 20
    // (created via "eval" function), or even
    // in the "storage" object - 30

    console.log(x); // ? - scope of "x" is undetermined at compile time

  }

  // organize recursion on 3 calls

  if (flag < 3) {
    foo(++flag);
  }

})(1);