csv-library-website/library/static/js/dropdown.js

filterSelection("all", "None");
function filterSelection(c, id) {
	resetDropDownButtons();
	var i;
  var button = document.getElementById(id);
	if(button){
		button.innerText = c;
		addClass(button, "activebtn");
	}
  var allpublications = document.getElementsByClassName("filter");
	if (c == "all") {
    for (i = 0; i < allpublications.length; i++) {
      addClass(allpublications[i], "show");
    }
  }
  else {
    for (i = 0; i < allpublications.length; i++) {
      removeClass(allpublications[i], "show");
      if (allpublications[i].className.indexOf(c) > -1) {
        addClass(allpublications[i], "show");
      }
    }
  }
}

function resetDropDownButtons(){
	document.getElementById("License").innerText = "License";
	document.getElementById("PubType").innerText = "Type";
	document.getElementById("Year").innerText = "Year";
	document.getElementById('booksearch').value= "";
	document.getElementById('booksearch').placeholder = "🔍 Search..";
	allactivebuttons = document.getElementsByClassName("activebtn");
	for(var i = 0;allactivebuttons.length; i++) {
		removeClass(allactivebuttons[i], "activebtn");
	}
}

function addClass(element, name) {
  var i, arr1, arr2;
  arr1 = element.className.split(" ");
  arr2 = name.split(" ");
  for (i = 0; i < arr2.length; i++) {
    if (arr1.indexOf(arr2[i]) == -1) {element.className += " " + arr2[i];}
  }
}

function removeClass(element, name) {
  var i, arr1, arr2;
  arr1 = element.className.split(" ");
  arr2 = name.split(" ");
  for (i = 0; i < arr2.length; i++) {
    while (arr1.indexOf(arr2[i]) > -1) {
      arr1.splice(arr1.indexOf(arr2[i]), 1);
    }
  }
  element.className = arr1.join(" ");
}