JSFiddle - React, Tailwind, and code Playground

HTML

<form name="form1">
<input name="d" />
</form>
<button onclick="up1('d', 'button1')">Up1</button>
<button onclick="up2('button2')">Up1</button>

JavaScript

function up1(fieldname, mul) {
    document.form1[fieldname].value = mul;
}

function up2(mul) {
    document.form1.d.value = mul;
}