This is how I implemented it for Jasny bootstrap input type in whole project commonly.
Hope this will help some one.
$('.fileinput').on("change.bs.fileinput", function (e) {
var file = $(e.delegateTarget, $("form")).find('input[type=file]')[0].files[0];
var fileExtension = file.name.split(".");
fileExtension = fileExtension[fileExtension.length - 1].toLowerCase();
var arrayExtensions = ["jpg", "jpeg", "png"];
if (arrayExtensions.lastIndexOf(fileExtension) == -1) {
alert('Only Images can be uploaded');
}
else {
if (file["size"] >= 4194304 && (fileExtension == "jpg" || fileExtension == "jpeg" || fileExtension == "png")) {
alert('Max 4 MB of file size can be uploaded.');
$(this).fileinput('clear');
}
}
});