JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="quantity1" class="quantity_class" />
<input type="submit" id="onclick1" class="quantity_class" value="Add to cart" />

JavaScript

$('#quantity1').keyup(function () {
    val = $(this).val();
    $('#onclick1').attr('onclick', 'func(1,'+val+')');
});