ECMAThe intention of this design is What?
First of all,Strongly recommendedThis post,understand delete
Next, we need to know what isGloblobject and window,execution context, andvariable object/activation objectFull stop
FunctionWhen defining variable or function, they become the property of globlobject, and they also haveDontDeleteAttribute of. Since he is a property of globobabject, of course he can pass
window.aPropTo visit la.
window.foo = 1If this display defines a property for an object, the property does not haveDontDelteThe of this attribute.
As long as there isDontDelete, cannot be