Bootstrap 4 Typeahead Plugin Examples

<div class="form-group">
    <input type="text" class="form-control" id="field-state" placeholder="State">
</div>

<script>
document.addEventListener('DOMContentLoaded', function(){
    var substringMatcher = function(strs) {
        return function findMatches(q, cb) {
            var matches, substringRegex;
            matches = [];

            substrRegex = new RegExp(q, 'i');

            $.each(strs, function(i, str) {
                if (substrRegex.test(str))
                    matches.push(str);
            })

            cb(matches);
        }
    }

    var states = ['Alabama', 'Alaska', 'Arizona', 'Arkansas', 'California',
        'Colorado', 'Connecticut', 'Delaware', 'Florida', 'Georgia', 'Hawaii',
        'Idaho', 'Illinois', 'Indiana', 'Iowa', 'Kansas', 'Kentucky', 'Louisiana',
        'Maine', 'Maryland', 'Massachusetts', 'Michigan', 'Minnesota',
        'Mississippi', 'Missouri', 'Montana', 'Nebraska', 'Nevada', 'New Hampshire',
        'New Jersey', 'New Mexico', 'New York', 'North Carolina', 'North Dakota',
        'Ohio', 'Oklahoma', 'Oregon', 'Pennsylvania', 'Rhode Island',
        'South Carolina', 'South Dakota', 'Tennessee', 'Texas', 'Utah', 'Vermont',
        'Virginia', 'Washington', 'West Virginia', 'Wisconsin', 'Wyoming'
    ];

    $('#field-state').typeahead(
    {
        hint: true,
        highlight: true,
        minLength: 1,
    },
    {
        name: 'state',
        source: substringMatcher(states)
    })
})
</script>