JSFiddle - React, Tailwind, and code Playground
by Vladimir
HTML
<form id="form_id" action="post100.html" method="post">
<fieldset>
<label for="Pinboard_entry" class="floatL">Text: </label>
<textarea id="Pinboard_entry" rows="6" cols="45" name="entry" class=""></textarea>
<div class="fieldNotes">
<span id="pinboardCharsCount">10000001</span> digits left
</div>
<br>
<div class="buttonArea">
<input class="fieldBtnSubmit" value="Submit" type="submit">
<input class="fieldBtnCancel" value="Reset" type="reset">
</div>
</fieldset>
</form>
JavaScript
var textarea = document.getElementById('Pinboard_entry');
textarea.value = "test";
$.post( "post100.html", $( "#form_id" ).serialize() );