Magento 2 Add Javascript

Question

I have the following code in a custom module for admin backend, which is not running.

tinymce.html

<textarea class="admin__control-textarea wysiwyg" data-bind="
    value: value,
    valueUpdate: valueUpdate,
    hasFocus: focused,
    attr: {
        name: inputName,
        cols: cols,
        rows: rows,
        'aria-describedby': noticeId,
        placeholder: placeholder,
        id: uid,
        disabled: disabled
    }"
/>

<script type="text/javascript">
    require(['jquery'], function($){
        $(document).ready(function() {
            alert("inside tinymce template");
        });
   });
</script>

This produces the following HTML code

<textarea class="admin__control-textarea wysiwyg" data-bind="
    value: value,
    valueUpdate: valueUpdate,
    hasFocus: focused,
    attr: {
         name: inputName,
         cols: cols,
         rows: rows,
         'aria-describedby': noticeId,
         placeholder: placeholder,
         id: uid,
         disabled: disabled
     }" name="caption" cols="15" rows="2" aria-describedby="notice-I1P21H3" placeholder="" id="I1P21H3"></textarea>

<script type="text/javascript">
     require(['jquery'], function($){
         $(document).ready(function() {
            alert("inside tinymce template");
         });
     });
</script>

However, the alert is never fired.