JSFiddle - React, Tailwind, and code Playground

HTML

<form action="#">
    <p>
        <input class="toFixed1" type="text" placeholder="Type a number"></input>
    </p>
    <p>
        <input class="toFixed1" type="text" placeholder="Type a number"></input>
    </p>
    <p>
        <input class="toFixed1" type="text" placeholder="Type a number"></input>
    </p>
    <button id="submitform" type="submit">test</button>
</form>

JavaScript

//when user clicks submit button
$('#submitform').click(function(){
    $(this).closest('form').find('.toFixed1').each(function(){
        var val = parseFloat($(this).val());
        //only perform operation on an actual number
        if(!isNaN(val)){
            //overwrite the value of the field with the reduced decimal number
            $(this).val(val.toFixed(1));
        }
        
    })
})