JSFiddle - React, Tailwind, and code Playground

JavaScript

function getISODateTime(d){
    // padding function
    var s = function(p){
        return (''+p).length<2?'0'+p:''+p;
    };
    
    // default parameter
    if (typeof d === 'undefined'){
        var d = new Date();
    };
    
    // return ISO datetime
    return d.getFullYear() + '-' +
        s(d.getMonth()+1) + '-' +
        s(d.getDate()) + ' ' +
        s(d.getHours()) + ':' +
        s(d.getMinutes()) + ':' +
        s(d.getSeconds());
}

    

alert(getISODateTime());