前端调试技巧

console.log(test());     // 1
delete test;
console.log(typeof test);     // undefined

var GLOBAL_OBJECT = this;

/* `foo` is created as a property of calling context Variable object,
which in this case is a Global object */

eval('var foo = 1;');
GLOBAL_OBJECT.foo; // 1

var o = { x: 1 };
delete o.x; // true
o.x; // undefined