hasOwnProperty style

gistfile1.js

var obj = {
  foo: 1,
  bar: 2
};

Object.prototype.oops = function(){};

// Meh.
for (var key in obj) {
    if (obj.hasOwnProperty(key)) {
        // ...
    }
}

// Better!
for (var key in obj) if (obj.hasOwnProperty(key)) {
    // ...
}

Pretty neat.