59naga/file0.js

## file0.js
window.addEventListener('popstate',function(){console.log(location.search)});
history.pushState(null,null,'?page=2');

## file1.html
<meta charset="UTF-8">
<script>
window.addEventListener('load',main,false);
function main(){
  var _title=document.title;
  var buttons=document.querySelectorAll('button');
  Array.prototype.forEach.call(buttons,function(button){
    button.onclick=function(){
      var query=Query.create(location.search);
      query.button=this.innerText;
      history.pushState(null,null,query.toString());
      window.dispatchEvent(document.createEvent('PopStateEvent'));
    }
  });

  window.addEventListener('popstate',function(event){
    var title=_title;
    var query=Query.create(location.search);
    if(query.hasOwnProperty('button')){
      title=query.button;
    }
    switch(query.button){
      case 'hoge':
        document.querySelector('pre').innerText=1;
        break;
      case 'fuga':
        document.querySelector('pre').innerText=2;
        break;
      case 'piyo':
        document.querySelector('pre').innerText=3;
        break;
      default:
        document.querySelector('pre').innerText=0;
        break;
    }
    document.title=title;//pushStateに適用される
  },false);
}

Query.create=function(search){return new Query(search)}
function Query(search){
  var self=this;
  Object.call(self);

  var search=search? search.substr(1): "";
  if(search){
    search.split('&').forEach(function(param){
      var param=param.split('=');
      var key=decodeURIComponent(param[0]);
      var value=param[1];
      if(value){
        value=decodeURIComponent(param[1]);
      }
      self[key]=value;
    });
  }
}
Query.prototype.toString=function(){
  var params=[];
  for(var key in this){
    if(this.hasOwnProperty(key)){
      var param=encodeURIComponent(key);
      if(this[key]){
        param+='='+encodeURIComponent(this[key]);
      }
      params.push(param);
    }
  }

  return params.length? "?"+params.join('&'): "";
}
</script>
<body>
  <button>hoge</button>
  <button>fuga</button>
  <button>piyo</button>
  <pre></pre>
</body>
	window.addEventListener('popstate',function(){console.log(location.search)});
	history.pushState(null,null,'?page=2');
	<meta charset="UTF-8">
	<script>
	window.addEventListener('load',main,false);
	function main(){
	var _title=document.title;
	var buttons=document.querySelectorAll('button');
	Array.prototype.forEach.call(buttons,function(button){
	button.onclick=function(){
	var query=Query.create(location.search);
	query.button=this.innerText;
	history.pushState(null,null,query.toString());
	window.dispatchEvent(document.createEvent('PopStateEvent'));
	}
	});

	window.addEventListener('popstate',function(event){
	var title=_title;
	var query=Query.create(location.search);
	if(query.hasOwnProperty('button')){
	title=query.button;
	}
	switch(query.button){
	case 'hoge':
	document.querySelector('pre').innerText=1;
	break;
	case 'fuga':
	document.querySelector('pre').innerText=2;
	break;
	case 'piyo':
	document.querySelector('pre').innerText=3;
	break;
	default:
	document.querySelector('pre').innerText=0;
	break;
	}
	document.title=title;//pushStateに適用される
	},false);
	}

	Query.create=function(search){return new Query(search)}
	function Query(search){
	var self=this;
	Object.call(self);

	var search=search? search.substr(1): "";
	if(search){
	search.split('&').forEach(function(param){
	var param=param.split('=');
	var key=decodeURIComponent(param[0]);
	var value=param[1];
	if(value){
	value=decodeURIComponent(param[1]);
	}
	self[key]=value;
	});
	}
	}
	Query.prototype.toString=function(){
	var params=[];
	for(var key in this){
	if(this.hasOwnProperty(key)){
	var param=encodeURIComponent(key);
	if(this[key]){
	param+='='+encodeURIComponent(this[key]);
	}
	params.push(param);
	}
	}

	return params.length? "?"+params.join('&'): "";
	}
	</script>
	<body>
	<button>hoge</button>
	<button>fuga</button>
	<button>piyo</button>
	<pre></pre>
	</body>