JSFiddle - React, Tailwind, and code Playground

JavaScript

var str,
    re;

str = "<select id='orderlist-0' name='orderitems[0].orderitem.OrderItemId'></select><span class='field-validation-valid' data-valmsg-for='orderitems[0].orderitem.OrderItemId' data-valmsg-replace='true'></span>";

re = /(\[)(\\@)(\])/g;

str = str.replace(re, '$11$3');

console.log(str);