Filepicker in BS 4.1.3
by Bianca Kuehweidner
HTML
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js"></script>
<form>
<div class="input-group mb-3">
<div class="custom-file">
<input type="file" class="custom-file-input" id="customFile" accept=".csv" name="branchCsv" required="">
<label class="custom-file-label" id="uploadLabel" for="customFile">Choose file</label>
</div>
<div class="input-group-append">
<button type="submit" id="submitBranchCsv" disabled="disabled" class="btn btn-success btn-upload">Import</button>
</div>
</div>
</form>
JavaScript
$('.custom-file-input').on('change',function(){
var fileName = $(this).val();
fileName = fileName.replace("C:\\fakepath\\", "");
$("#submitBranchCsv").prop("disabled", false);
$("#uploadLabel").text(fileName);
});