JSFiddle - React, Tailwind, and code Playground

HTML

<div id="checkboxdiv">
<input type="checkbox" name="test" value=1 onclick="getVals();" checked/>
<input type="checkbox" name="test" value=2 onclick="getVals();" checked/>
<input type="checkbox" name="test" value=3 onclick="getVals();" checked/>
<input type="checkbox" name="test" value=4 onclick="getVals();" checked/>
</div>

JavaScript

function getVals(){
    var values=$("#checkboxdiv input[name=test]:checked").map (function (){
      return $(this).val();}).get().join(',');
    alert(values);
}