JSが連想を実現し、国や地域の名前を自動的に補完する機能です。


1.JS部分

function autocomplete(inp, arr) {
 /*         :               */
 var currentFocus;
 /*    -        */
 inp.addEventListener("input", function(e) {
   var a, b, i, val = this.value;
   /*              */
   closeAllLists();
   if (!val) { return false;}
   currentFocus = -1;
   /*    */
   a = document.createElement("DIV");
   a.setAttribute("id", this.id + "autocomplete-list");
   a.setAttribute("class", "autocomplete-items");
   /*   DIV   */
   this.parentNode.appendChild(a);
   /*    ...*/
   for (i = 0; i < arr.length; i++) {
    /*                    */
    if (arr[i].substr(0, val.length).toUpperCase() == val.toUpperCase()) {
     /*        DIV*/
     b = document.createElement("DIV");
     /*        */
     b.innerHTML = "<strong>" + arr[i].substr(0, val.length) + "</strong>";
     b.innerHTML += arr[i].substr(val.length);
     /*insert a input field that will hold the current array item's value:*/
     b.innerHTML += "<input type='hidden' value='" + arr[i] + "'>";
     /*execute a function when someone clicks on the item value (DIV element):*/
     b.addEventListener("click", function(e) {
       /*insert the value for the autocomplete text field:*/
       inp.value = this.getElementsByTagName("input")[0].value;
       /*close the list of autocompleted values,
       (or any other open lists of autocompleted values:*/
       closeAllLists();
     });
     a.appendChild(b);
    }
   }
 });
 /*execute a function presses a key on the keyboard:*/
 inp.addEventListener("keydown", function(e) {
   var x = document.getElementById(this.id + "autocomplete-list");
   if (x) x = x.getElementsByTagName("div");
   if (e.keyCode == 40) {
    /*If the arrow DOWN key is pressed,
    increase the currentFocus variable:*/
    currentFocus++;
    /*and and make the current item more visible:*/
    addActive(x);
   } else if (e.keyCode == 38) { //up
    /*If the arrow UP key is pressed,
    decrease the currentFocus variable:*/
    currentFocus--;
    /*and and make the current item more visible:*/
    addActive(x);
   } else if (e.keyCode == 13) {
    /*If the ENTER key is pressed, prevent the form from being submitted,*/
    e.preventDefault();
    if (currentFocus > -1) {
     /*and simulate a click on the "active" item:*/
     if (x) x[currentFocus].click();
    }
   }
 });
 function addActive(x) {
  /*a function to classify an item as "active":*/
  if (!x) return false;
  /*start by removing the "active" class on all items:*/
  removeActive(x);
  if (currentFocus >= x.length) currentFocus = 0;
  if (currentFocus < 0) currentFocus = (x.length - 1);
  /*add class "autocomplete-active":*/
  x[currentFocus].classList.add("autocomplete-active");
 }
 function removeActive(x) {
  /*a function to remove the "active" class from all autocomplete items:*/
  for (var i = 0; i < x.length; i++) {
   x[i].classList.remove("autocomplete-active");
  }
 }
 function closeAllLists(elmnt) {
  /*close all autocomplete lists in the document,
  except the one passed as an argument:*/
  var x = document.getElementsByClassName("autocomplete-items");
  for (var i = 0; i < x.length; i++) {
   if (elmnt != x[i] && elmnt != inp) {
    x[i].parentNode.removeChild(x[i]);
   }
  }
 }
 /*execute a function when someone clicks in the document:*/
 document.addEventListener("click", function (e) {
   closeAllLists(e.target);
   });
}

/*   -           */
var countries = ["Afghanistan","Albania","Algeria","Andorra","Angola","Anguilla","Antigua & Barbuda","Argentina","Armenia","Aruba","Australia","Austria","Azerbaijan","Bahamas","Bahrain","Bangladesh","Barbados","Belarus","Belgium","Belize","Benin","Bermuda","Bhutan","Bolivia","Bosnia & Herzegovina","Botswana","Brazil","British Virgin Islands","Brunei","Bulgaria","Burkina Faso","Burundi","Cambodia","Cameroon","Canada","Cape Verde","Cayman Islands","Central Arfrican Republic","Chad","Chile","China","Colombia","Congo","Cook Islands","Costa Rica","Cote D Ivoire","Croatia","Cuba","Curacao","Cyprus","Czech Republic","Denmark","Djibouti","Dominica","Dominican Republic","Ecuador","Egypt","El Salvador","Equatorial Guinea","Eritrea","Estonia","Ethiopia","Falkland Islands","Faroe Islands","Fiji","Finland","France","French Polynesia","French West Indies","Gabon","Gambia","Georgia","Germany","Ghana","Gibraltar","Greece","Greenland","Grenada","Guam","Guatemala","Guernsey","Guinea","Guinea Bissau","Guyana","Haiti","Honduras","Hong Kong China","Hungary","Iceland","India","Indonesia","Iran","Iraq","Ireland","Isle of Man","Israel","Italy","Jamaica","Japan","Jersey","Jordan","Kazakhstan","Kenya","Kiribati","Kosovo","Kuwait","Kyrgyzstan","Laos","Latvia","Lebanon","Lesotho","Liberia","Libya","Liechtenstein","Lithuania","Luxembourg","Macau China","Macedonia","Madagascar","Malawi","Malaysia","Maldives","Mali","Malta","Marshall Islands","Mauritania","Mauritius","Mexico","Micronesia","Moldova","Monaco","Mongolia","Montenegro","Montserrat","Morocco","Mozambique","Myanmar","Namibia","Nauro","Nepal","Netherlands","Netherlands Antilles","New Caledonia","New Zealand","Nicaragua","Niger","Nigeria","North Korea","Norway","Oman","Pakistan","Palau","Palestine","Panama","Papua New Guinea","Paraguay","Peru","Philippines","Poland","Portugal","Puerto Rico","Qatar","Reunion","Romania","Russia","Rwanda","Saint Pierre & Miquelon","Samoa","San Marino","Sao Tome and Principe","Saudi Arabia","Senegal","Serbia","Seychelles","Sierra Leone","Singapore","Slovakia","Slovenia","Solomon Islands","Somalia","South Africa","South Korea","South Sudan","Spain","Sri Lanka","St Kitts & Nevis","St Lucia","St Vincent","Sudan","Suriname","Swaziland","Sweden","Switzerland","Syria","Taiwan China","Tajikistan","Tanzania","Thailand","Timor L'Este","Togo","Tonga","Trinidad & Tobago","Tunisia","Turkey","Turkmenistan","Turks & Caicos","Tuvalu","Uganda","Ukraine","United Arab Emirates","United Kingdom","United States of America","Uruguay","Uzbekistan","Vanuatu","Vatican City","Venezuela","Vietnam","Virgin Islands (US)","Yemen","Zambia","Zimbabwe"];

/*    */
autocomplete(document.getElementById("myInput"), countries);
2.CSS部分

* { box-sizing: border-box; }
body {
 font: 16px Arial; 
}
.autocomplete {
 /*the container must be positioned relative:*/
 position: relative;
 display: inline-block;
}
input {
 border: 1px solid transparent;
 background-color: #f1f1f1;
 padding: 10px;
 font-size: 16px;
}
input[type=text] {
 background-color: #f1f1f1;
 width: 100%;
}
input[type=submit] {
 background-color: DodgerBlue;
 color: #fff;
}
.autocomplete-items {
 position: absolute;
 border: 1px solid #d4d4d4;
 border-bottom: none;
 border-top: none;
 z-index: 99;
 /*position the autocomplete items to be the same width as the container:*/
 top: 100%;
 left: 0;
 right: 0;
}
.autocomplete-items div {
 padding: 10px;
 cursor: pointer;
 background-color: #fff; 
 border-bottom: 1px solid #d4d4d4; 
}
.autocomplete-items div:hover {
 /*when hovering an item:*/
 background-color: #e9e9e9; 
}
.autocomplete-active {
 /*when navigating through the items using the arrow keys:*/
 background-color: DodgerBlue !important; 
 color: #ffffff; 
}
3.HTML部分

<!--             -->
<form autocomplete="off" action="/action_page.php">
 <div class="autocomplete" style="width:300px;">
  <input id="myInput" type="text" name="myCountry" placeholder="          ...">
 </div>
 <input type="submit">
</form>
4.効果図

以上はJSが連想を実現して、自動で国家あるいは地区の名称の機能の詳しい内容を補って、もっと多いJSの連想、自動で機能の資料を補って私達のその他の関連している文章に注意して下さい!