Saving Text to Session If The Page Is Accidentally Refreshed

Get the text field that you want to track

let field = document.getElementById('field');

Assign value to the field if accidentally refreshed the page

if(sessionStorage.getItem('autosave')){
 field.value = sessionStorage.getItem('autosave');
}

Save value to session when field value change

field.addEventListener('change', function(){
 sessionStorage.setItem('autosave', field.value);
});