JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" name="BoqTextBox" id="BoqTextBox" value="0" />
<input type="Button" id='AddButton' value="+" />
<input type="text" name="BoqTextBoxsub" id="BoqTextBoxsub" value="0" />
<input type="Button" id='SubButton' value="-" />

JavaScript

$('#AddButton').on('click', function () {
    var input = $('#BoqTextBox');
    input.val(parseFloat(input.val(), 10) + 1);
})
$('#SubButton').on('click', function(){

var input=$('#BoqTextBoxsub');
input.val(parseFloat(input.val(), 10) - 1);

})