How to add autocomplete to an input field in JavaScript


    

How to add autocomplete to an input field in JavaScript


    <!DOCTYPE html>
        <html>
        <head>
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
        <style>
        * {
        box-sizing: border-box;
        }

        body {
        font: 16px Arial;  
        }

        /*the container must be positioned relative:*/
        .autocomplete {
        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; 
        }

        /*when hovering an item:*/
        .autocomplete-items div:hover {
        background-color: #e9e9e9; 
        }

        /*when navigating through the items using the arrow keys:*/
        .autocomplete-active {
        background-color: DodgerBlue !important; 
        color: #ffffff; 
        }
        </style>
        </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">
        <div class="autocomplete" style="width:300px;">
            <input id="myInput" type="text" name="myCountry" placeholder="Country">
        </div>
        <input type="submit">
        </form>

        <script>
        function autocomplete(inp, arr) {
        /*the autocomplete function takes two arguments,
        the text field element and an array of possible autocompleted 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);
        });
        }

        /*An array containing all the country names in the world:*/
        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","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","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","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"];

        /*initiate the autocomplete function on the "myInput" element, and pass along the countries array as possible autocomplete values:*/
        autocomplete(document.getElementById("myInput"), countries);
        </script>

        </body>
        </html>

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