将CSS应用于通过window.open（）打开的外部页面

Question

I am opening an external page upon click of a button. This is working by using window.open(), the requirement is to apply a specific CSS to the element of external page like changing the font color.

Can anyone please help me to understand on how to apply CSS to the elements of a external page after opening the external page using window.open()

Answer 1

You can't, end of story. This is a security issue built into browsers so scripts from other sites cannot modify other pages. This would be a disaster if browsers allowed this.

Answer 2

You can access the DOM of the child window by accessing the document property of the returned value of the window.open method.

Example:

var popup = window.open("test.html");
popup.document.body.style.backgroundColor = "black";

There will be security issues to deal with when trying to achieve such a goal when the parent domain and child domain differ due to same origin policies.