Adding event listener on month change event in an ion-datetime object?

const element = document.getElementById('Date-Time');
element.addEventListener('ionChange', function (event) {    
    
    console.log(JSON.stringify(event));
    console.log(JSON.stringify(event.detail));
    console.log(JSON.stringify(event.detail.value));
    
    const dateFormat = event.detail.value.split('T')[0];
    alert(dateFormat);

}, false);

if one changes the month using the arrows forward < or backward > arrow or if I slide the page to change the month, how can one trigger an event with the month value and the year value displayed after the month changes?

You can try this

//your .ts
onDateChange( event: any ){
  console.log(event.detail.value.substring(0, 7)); // YYYY-MM date format
}

//your .html
<ion-datetime presentation="month-year" (ionChange)="onDateChange( $event )"></ion-datetime>