How to Detect Browser Back Button event - Cross Browser

Question

How do you definitively detect whether or not the user has pressed the back button in the browser?

How do you enforce the use of an in-page back button inside a sin

Answer 1

I had been struggling with this requirement for quite a while and took some of the solutions above to implement it. However, I stumbled upon an observation and it seems to work across Chrome, Firefox and Safari browsers + Android and iPhone

On page load:

window.history.pushState({page: 1}, "", "");

window.onpopstate = function(event) {

  // "event" object seems to contain value only when the back button is clicked
  // and if the pop state event fires due to clicks on a button
  // or a link it comes up as "undefined" 

  if(event){
    // Code to handle back button or prevent from navigation
  }
  else{
    // Continue user action through link or button
  }
}

Let me know if this helps. If am missing something, I will be happy to understand.