matix

var array = ["zero","first","second","third","fourth","fifth"];
var closures = [];

for(var i=0, l=array.length; i<l; i++){
  closures.push(function(){return array[i]});
}

closures[3]();  
// Expected "third", but actually returns 'undefined', 
// because js did not create a separate scope for the "for" block

matix

function changeAllAnchorColor(color){
  var anchors = document.body.getElementsByTagName("a");
  for (var i = 0, l = anchors.length; i<l; i++){
    anchors[i].style.color = color;
  }
}

var changeAllAnchorColorDesynched = desync(changeAllAnchorColor);

document.body.innerHTML = "<div id=container><a href=#>LOL This code does nothing...</a></div>";

matix

function benchmark(fn, id, it){
  id = id || new Date().toString();
  it = it || 100000;
  if(typeof fn == "function"){
    console.time(id);
    for (var i = 0; i< it; i++) fn();
    console.timeEnd(id);
  }
}