JSFiddle - React, Tailwind, and code Playground

HTML

<script src="//cdnjs.cloudflare.com/ajax/libs/ckeditor/4.3.2/ckeditor.js"></script>
<body>
<div contenteditable="true" class="editable-element cke_editable cke_editable_inline" id="content" name"content" style="border:2px solid black"></div>
    
<div style="margin-top: 150px;">
    <input type="button" id="btnSpace" value="space"/>    
    <input type="button" id="btnLetter" value="Letter A"/>    
</div>
</body>

JavaScript

$(function(){
    var editor = CKEDITOR.instances["content"];
    
    $("#btnSpace").on("click", function() {
        editor.focus();
        editor.insertText(" ");
    });
    
     $("#btnLetter").on("click", function() {
        editor.focus();
        editor.insertText("A");
    });
    
});