In this article I will explain with an example, how to prevent Bootstrap Modal Popup from closing when clicked outside.
 
 
Prevent Bootstrap Modal Popup from closing when clicked outside when opened using Button
The following HTML Markup consists of an HTML DIV and an HTML Button.
The HTML DIV has been assigned with a CSS class modal and role dialog, so that it opens as Bootstrap Modal Popup.
The Button will open the Bootstrap Modal Popup when clicked. The Button has been assigned with two attributes data-backdrop="static" and data-keyboard="false" which disable the closing of the Bootstrap Modal Popup when clicked outside.
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
</head>
<body>
    <button type="button" class="btn btn-primary" data-toggle="modal" data-target="#simpleModal" data-backdrop="static" data-keyboard="false">Button 1</button>
    <div id="simpleModal" class="modal" tabindex="-1" role="dialog">
        <div class="modal-dialog" role="document">
            <div class="modal-content">
                <div class="modal-header">
                    <h5 class="modal-title">Customer Details Form</h5>
                    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                        <span aria-hidden="true">&times;</span>
                    </button>
                </div>
                <div class="modal-body">
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                </div>
                <div class="modal-footer">
                    <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
                </div>
            </div>
        </div>
    </div>
    <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous"/>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
</body>
</html>
 
 
Prevent Bootstrap Modal Popup from closing when clicked outside when opened using JavaScript
The following HTML Markup consists of an HTML DIV and an HTML Button.
The HTML DIV has been assigned with a CSS class modal and role dialog, so that it opens as Bootstrap Modal Popup.
The Button will open the Bootstrap Modal Popup when clicked.
Inside the jQuery document ready event handler, the Button has been assigned with a click event handler.
When the Button is clicked, the HTML DIV is referenced using jQuery and its modal function is called along with properties data-backdrop: "static" and data-keyboard: false which disables the closing of the Bootstrap Modal Popup when clicked outside.
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
    <title></title>
</head>
<body>
    <button type="button" id="button2" class="btn btn-danger" data-toggle="modal">Button 2</button>
    <div id="simpleModal" class="modal" tabindex="-1" role="dialog">
        <div class="modal-dialog" role="document">
            <div class="modal-content">
                <div class="modal-header">
                    <h5 class="modal-title">Customer Details Form</h5>
                    <button type="button" class="close" data-dismiss="modal" aria-label="Close">
                        <span aria-hidden="true">&times;</span>
                    </button>
                </div>
                <div class="modal-body">
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                </div>
                <div class="modal-footer">
                    <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
                </div>
            </div>
        </div>
    </div>
    <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous"/>
    <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
    <script type="text/javascript">
        $(function () {
            $("#button2").click(function () {
                $("#simpleModal").modal({ backdrop: "static ", keyboard: false });
            });
        });
    </script>
</body>
</html>
 
 
Screenshot
Prevent Bootstrap Modal Popup from closing when clicked outside
 
 
Browser Compatibility

The above code has been tested in the following browsers.

Internet Explorer  FireFox  Chrome  Safari  Opera 

* All browser logos displayed above are property of their respective owners.

 
 
Demo
 
 
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