TypeError: $(…).modal is not a function

The $(…).modal is not a function is usually caused because scripts are loaded in the wrong order . The browser will execute the scripts in the order it finds them. If in a script you attempt to access an element that hasn't been reached yet then you will get an error. Make sure that you don't have a script above one that it requires.
TypeError: $(…).modal is not a function with bootstrap Modal

Bootstrap : TypeError

For example, bootstrap depends on jQuery , so jQuery must be referenced first. So, you must called the jquery.min.js and then bootstrap.min.js like the following:
<script src="/jquery-3.3.1.min.js"></script> <script src="/bootstrap.min.js"></script>

bootstrap.js

Bootstrap modal does not work well with jQuery UI dialog The bootstrap Modal error is actually the result of you not including bootstrap's javascript before calling the modal function. Modal is defined in bootstrap.js and not in jQuery . It's also important to note that bootstrap actually needs jQuery to define the modal function , so it's vital that you include jQuery before including bootstrap's javascript. To avoid such error just be sure to include jQuery then bootstrap's javascript before you call the modal function.

Plugin dependencies

Some plugins and CSS components depend on other plugins. If you include plugins individually, make sure to check for these dependencies in the docs. Also note that all plugins depend on jQuery (this means jQuery must be included before the plugin files).

Multiple jQuery instances

javascript TypeError: $(...).modal is not a function with bootstrap Modal Sometimes this warning may also be shown if jQuery is declared more than once in your code. The second jQuery declaration prevents bootstrap.js from working correctly. The problem is due to having jQuery instances more than one time. Take care if you are using many files with multiples instance of jQuery. Just leave one instance of jQuery and your code will work.