A JavaScript fill-in question

Fill in the blanks so that the following alert (0) can be correctly displayed. At least two different ideas are listed.

Window. alert = function () {}; ______; alert (0 );

Solution:

Method 1:

Window. alert = function () {}; delete window. alert; alert (0 );

Getting started with the delete OPERATOR: https://developer.mozilla.org/en/JavaScript/Reference/Operators/delete

It is worth noting that when we mention the return value of the operator, it is described as follows:

Returns false only if the property exists and cannot be deleted. It returns true in all other cases.

If an attribute exists and cannot be deleted, false is returned. Otherwise, true is returned.

Method 2:
Create an iframe and obtain the iframe window. alert to the window. alert of the current page.

Source: mango station Original: Click to view