如何从文档中删除属性？

Question

I'm trying to manipulate document.oncopy property for my tests. And can't figure it out how to accomplish that. I've already tried the following approach.

I wonder why it won't delete the property.

 Object.defineProperty(document, 'oncopy', { configurable: true, get () {}, }); console.log('oncopy' in document);

 delete document.oncopy; console.log('oncopy' in document);

'oncopy' in document says true .

Answer 1

The method exists (as a getter/setter) on Document.prototype . If you want to completely remove it from the prototype chain so that the in test results in false , remove it from the prototype object:

 delete Document.prototype.oncopy console.log('oncopy' in document);