JSFiddle - React, Tailwind, and code Playground

HTML

<body onload="addOption_list()">
        <form name="register_form" action="" id="register_form" >
       
    
     
                <select name="day_list"><option value="">Day</option></select>
                <select name="month_list"><option value="">Month</option></select>
                <select name="year_list"><option value="">Year</option></select>
          
     
        </form>

JavaScript

var today=new Date();
var thisyear=today.getFullYear();
function addOption(selectbox, text, value) {
    var optn = document.createElement("option");
    optn.text = text;
    optn.value = value;
    selectbox.options.add(optn);
}
function addOption_list() {
     
    for (var i=1; i <= 31;++i) {
        addOption(document.register_form.day_list,i,i);
    }
        for (var i=1; i <= 12;++i) {
        addOption(document.register_form.month_list,i,i);
    }
        for (var i=(thisyear); i >= (thisyear-100);--i) {
        addOption(document.register_form.year_list,i,i);
    }
}