I Would Like To Intercept All Click Events On My Document

I am beginner in JavaScript. I would like to intercept all click events on my document. I use this function for that:

document.onmousedown=click;.

It works well. But I would like to continue the execution code on a other button or anything else.

Example:

1)Click anywhere intercept click->Execute the code in function click().
2)Click on a link…. intercept click -> Execute the code in function
click() ->Load the link(http://test.html)
3)Click on a button… intercept click-> Execute the code in function
click() ->Execute the code for the button(submit, or other javascript)