JSFiddle - React, Tailwind, and code Playground

HTML

<input type="button" id="JAN"  value="JAN"/>
<input type="button" id="FEB" value="FEB"/>
<input type="button" id="MAR" value="MAR"/>

JavaScript

$(function(){
    function navbarMONTH(arg) {
       // var datas = eval('(' + arg + ')')
        var datas={"year":2015};
        var jsonMONTH = {
            "a1": "JAN",
            "a2": "FEB",
    		"a3" : "MAR",
            "b1": "01",
            "b2" : "02",
    		"b3" : "03"
        }
     

      
    for (var countMONTH = 1; countMONTH < 4; countMONTH++) {	
            var buttonMONTH = document.querySelectorAll('#' + jsonMONTH['a' + countMONTH])
                buttonMONTH[0].MONTH=countMONTH
            var varMONTH = jsonMONTH['b' + countMONTH]
    		var nb_buttonMONTH = buttonMONTH.length
                           
    			buttonMONTH[0].onclick = function () {
                        alert('chargeCal(' + this.MONTH + ',' + datas.year + ')')
    				}
    			}
        
    }

navbarMONTH();
})