Show next button only if an answer is selected

Add this JS to your question:
Qualtrics.SurveyEngine.addOnReady(function() {
var qobj = this;
qobj.hideNextButton();
jQuery("#"+qobj.questionId+" [type=checkbox]").click(function() {
if(this.checked) qobj.showNextButton();
else qobj.hideNextButton();
});
});

it works thanks a lot

Hello Mates, 

Unfortunately, the "Next" button disappears if I use this code, but after I have completed a questions the ‘NEXT Button’ does not reappear. Could you please provide guidance on how to resolve this?

Hi @csnagy,

→ The next button is initially hidden in the above code, that’s why it is disappeared.

→ You must have declared it globally at the start of the code due to which the next button is disappeared for all the questions. Enter the JS in between the element of the following, it will only work  for the particular question and not the whole survey.
 

Qualtrics.SurveyEngine.addOnReady(function()
{

    Your JS Code
});