I open a website. What if I want to change the layout or interaction of the site? Open the console can be modified, but open the console modified page refresh will be invalid!

so I thought that if I saved the modified code to a file, and then set it in the console to load the saved file automatically (maybe html, css, js, etc.) when I opened a website, wouldn"t it be tantamount to attaching my own code to the website?

especially want to achieve this effect, I do not know whether it can be achieved? (does the browser console have this function? is there a plug-in like or? )

Note , I don"t have the source code of the website, so I can"t add these directly to the code of the website! My goal is to diy any website!

if you use curl to grab content and change it, if it is js dynamically loading content will involve cross-domain problems! It won"t work.