test010.js

function bench(c, func) {
  var d = Date.now();
  try {
    func();
  } catch(e) {
    print(e);
  }
  print(c + " : " + (Date.now() - d));
}

bench('pure', function() {
  var ary = [];
  ary.length = (1 << 24) - 1;
  ary.length = 0;
});

bench('tainted', function() {
  "use strict";
  var ary = [];
  Object.defineProperty(ary, '0', { value: "OK" });
  ary.length = (1 << 24) - 1;
  ary.length = 1;
  // ary.length = 0;
});

bench('tainted2', function() {
  "use strict";
  var ary = [];
  Object.defineProperty(ary, '0', {
    enumerable: true,
    configurable: true,
    writable: true,
    value: "OK"
  });
  ary.length = (1 << 24) - 1;
  ary.length = 1;
  // ary.length = 0;
});