Answers for "js unselect all option select"

javascript get all select options

var options = document.getElementById('mySelectID').options;
for (let i = 0; i < options.length; i++) { 
  console.log(options[i].value);//log the value
}

js clear all select options

for (var option of document.querySelectorAll('#DropList option'))
{ 
  option.remove();
}