Get names of checkbox inside input field via JS

I want to get names of the checked boxes in the text input field below in this format : name1 , name2 , name3 :

<input class="iput" type="checkbox" name="E33" value="33"/> A 
<input class="iput" type="checkbox" name="E34" value="33"/> B
<input class="iput" type="checkbox" name="E66" value="33"/> C

<input type="text" id="sku" name="SKU" placeholder="show names here"/> 

Have tried multiple times but nothings working.