如果选中复选框切换，则在切换div中输入所需的输入字段

I use a script to toogle some div´s with javascript. I want to make some input fields "required" in the toogle div if the checkbox is checked to show the toogle div.

Can someone figure it out ? that is work?

function show(id) { 
    if(document.getElementById) { 
        var mydiv = document.getElementById(id); 
        mydiv.style.display = (mydiv.style.display=='block'?'none':'block'); 
    }
} 

var $myCheckbox = $('#neu_ma'),
$required   = $('.required');

$myCheckbox.on('click', function() {
this.checked ? $required.prop('required', true) : $required.prop('required', false);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form method="post" name="berechtigungsantrag">
<fieldset>
    <legend><input type="checkbox" name="neu_ma" id="neu_ma" onclick="javascript:show('neuer_mitarbeiter');"> Neuer Mitarbeiter </legend>
                    
<div style="display: none" id="neuer_mitarbeiter">
                                    
                <label for="eintritt_datum">Eintrittsdatum:</label>
                <div><input type="date" name="eintritt_datum" id="eintritt_datum" class="required" /></div>
                    
                <label for="befristung_datum">Befristungsdatum:</label>
        <div><input type="date" name="befristung_datum" id="befristung_datum"/></div>
    
</div>

    </fieldset><!-- End of fieldset -->
 
<input class="btn" type="submit" value="Speichern" name=save />

</form>

</div>

Answer:

You're trying to listen an element id that does not exist(neu_ma) - you haven't given your checkbox an id.

<input type="checkbox" name="neu_ma" onclick="javascript:show('neuer_mitarbeiter');">

So just give it an ID:

<input type="checkbox" name="neu_ma" id="neu_ma" onclick="javascript:show('neuer_mitarbeiter');">

This is just an example how you could do it:

Add some specific class to inputs that need to be affected by the state of your checkbox.

I made an example HTML:

<form>
    <input type="checkbox" id="myCheckbox" />
    <input type="text" class="required" />
    <input type="text" />
    <input type="text" class="required" />

    <button type="submit">Submit</button>
</form>

As you can see, some of the inputs have a class called "required".

Next I check checkbox status(checked or not). And depending on the result make elements with "required" class required(or not) using jQuery's prop() method.

Working example:

var $myCheckbox = $('#myCheckbox'),
    $required   = $('.required');

$myCheckbox.on('click', function() {
    this.checked ? $required.prop('required', true) : $required.prop('required', false);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<form>
    <input type="checkbox" id="myCheckbox" />
    <input type="text" class="required" />
    <input type="text" />
    <input type="text" class="required" />
    <button type="submit">Submit</button>
</form>

</div>