JSFiddle - React, Tailwind, and code Playground

HTML

<div id="crm-submit-buttons" class="crm-submit-buttons">
    <span class="crm-button crm-button-type-upload crm-button_qf_Register_upload"><input onclick="return submitOnce(this,'Register','Processing');" class="form-submit default" name="_qf_Register_upload" value="Continue &gt;&gt;" type="submit" id="_qf_Register_upload-bottom"></span>
</div>

JavaScript

$('#_qf_Register_upload-bottom').val('Submit');