bootstrap modal not showing code example

Example 1: bootstrap show modal on page load

<script type="text/javascript">
    $(window).on('load',function(){
        $('#myModal').modal('show');
    });
</script>

Example 2: bootstrap modal not close

$('#MymodalPreventScript').modal({
    		backdrop: 'static',
    		keyboard: false
		});

Example 3: .show() and .hide not working for bootstrap modal

<button class="button primary" id="buy" style="text-decoration:none;" type="button">Review and confirm</button>

<div class="modal-bootstrap fade bs-example-modal-sm" id="myModal" tabindex="-1" role="dialog" aria-labelledby="smallModalLabel" aria-hidden="true">
    <!-- modal contents -->
</div>

<script type="text/javascript">
$("#buy").click(function () {
    var a = 4;
    if (a == 5) {
        alert("if");
        $('#myModal').modal('show');
    } else {
        alert("else");
        $('#myModal').modal('hide');
    }
});
</script>

Example 4: input doesnt work on open modal bootstrap

Remove in div.modal:
tabindex="-1"