带括号的回调函数-Javascript

Question

在以下代码中，如果我在alertFinished中的doHomework上加上括号，为什么在“开始数学作业”之前发出“完成作业”警报？

function doHomework(subject, callback) {
  alert(`Starting my ${subject} homework.`);
  callback();
}

function alertFinished(){
  alert('Finished my homework');
}

doHomework('math', alertFinished())
//With parentheses;