Set autocomplete input field display value different from actual value

Question

I have a text field in my form which is filled using this autocomplete script. When a value is selected from the autocomplete suggestions, I want the field to be filled with the displayed value from the suggestions, (stored in array arr), but I want a different value to be submitted along with the POST request when the form is submitted (stored in array arr2).

The code:

b.innerHTML += "<input type='hidden' value = '" + arr[i] + "'>";
b.addEventListener("click", function(e) {
    inp.value = this.getElementsByTagName("input")[0].value;
    closeAllLists();
});
a.appendChild(b);

arr array contains the values that should be displayed, while another array arr2 contains the actual values that should be passed during the POST request.

What I have tried already:

1) I tried using the data-value property to hold the actual values and tried to set it as inp.value but in that case when I click a suggestion, it does not get autofilled.

b.innerHTML += "<input type='hidden' data-value = '" + arr2[i] + "' value = '" + arr[i] + "'>";
b.addEventListener("click", function(e) {
    inp.value = this.getElementsByTagName("input")[0].data-value;
    closeAllLists();
});
a.appendChild(b);

2) I tried setting the value property directly to the values from arr2 but then on clicking a suggestion, the input field gets filled with the value that has to be passed, and not the one that has to be displayed. Code below:

b.innerHTML += "<input type='hidden' value = '" + arr2[i] + "'>";
b.addEventListener("click", function(e) {
    inp.value = this.getElementsByTagName("input")[0].value;
    closeAllLists();
});
a.appendChild(b);

Answer 1

I don't think it's a good idea to have two separated arrays when their data related. I prefer to think on pairs. So, I used arr (and countries in the W3CSchools example) as JSON with:

var countries = {
  "Afghanistan": "af",
  "Algeria": "al",
  "República Argentina": "ar",
  "Belgium": "be",
  "Chile": "ch",
};

That's taking arr for keys and arr2 for values.

Object.keys(countries) will be the array for the 2nd. parameter of autocomplete function. In the call:,

autocomplete(document.getElementById("myInput"), Object.keys(countries));

When submitting (onSubmit), you can assign the value to the hidden field, which must have a name attribute

<form [...] onsubmit="prepareData()" >

And then a function

function prepareData() {
  document.getElementById("myHiddenField").value = countries[document.getElementById("myInput").value];
}

I applied this to the W3CSchools example, here is the working example

function getCountry() {
  // I just alert the value, this snippet does not go anywhere
  alert( countries[document.getElementById("myInput").value]);
}


function autocomplete(inp, arr) {
  /*the autocomplete function takes two arguments,
  the text field element and an json (array) of possible autocompleted PAIR OF values:*/
  var currentFocus;
  /*execute a function when someone writes in the text field:*/
  inp.addEventListener("input", function(e) {
      var a, b, i, val = this.value;
      /*close any already open lists of autocompleted values*/
      closeAllLists();
      if (!val) { return false;}
      currentFocus = -1;
      /*create a DIV element that will contain the items (values):*/
      a = document.createElement("DIV");
      a.setAttribute("id", this.id + "autocomplete-list");
      a.setAttribute("class", "autocomplete-items");
      /*append the DIV element as a child of the autocomplete container:*/
      this.parentNode.appendChild(a);
      /*for each item in the array...*/
      for (i = 0; i < arr.length; i++) {
        /*check if the item starts with the same letters as the text field value:*/
        if (arr[i].substr(0, val.length).toUpperCase() == val.toUpperCase()) {
          /*create a DIV element for each matching element:*/
          b = document.createElement("DIV");
          /*make the matching letters bold:*/
          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);
      });
}


/*A JSON containing all the country names in the world:*/

var countries={"Afghanistan":"af","Algeria":"al","Argentina":"ar","Belgium":"be","Chile":"ch"};
/*initiate the autocomplete function on the "myInput" element, and pass along the countries array as possible autocomplete values:*/

autocomplete(document.getElementById("myInput"), Object.keys(countries));

* {
  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;
  cursor: pointer;
}
.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; 
}

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
</head>     

<body>

<h2>Autocomplete</h2>

<p>Start typing:</p>

<!--Make sure the form has the autocomplete function switched off:-->
<form autocomplete="off" action="/action_page.php" onsubmit="getCountry()">
  <div class="autocomplete" style="width:300px;">
    <input id="myInput" type="text" name="myCountry" placeholder="Country">
  </div>
  <input type="submit">
</form>

</body>
</html>

Answer 2

Create a new hidden field which will hold the value that has to be passed and process it later.

c = document.createElement("DIV");
c.innerHTML = "<input type='hidden' value = '" + arr2[i] + "' name = 'newID'>";
this.parentNode.appendChild(c);