Append()，One()的jQuery到JavaScript的转换

// jQuery代码
$('#myElement').append('<p>Hello World!</p>');

// JavaScript代码
var element = document.getElementById('myElement');
var paragraph = document.createElement('p');
paragraph.textContent = 'Hello World!';
element.appendChild(paragraph);

// jQuery代码
$('#myElement').one('click', function() {
  console.log('Clicked!');
});

// JavaScript代码
var element = document.getElementById('myElement');
function clickHandler() {
  console.log('Clicked!');
  element.removeEventListener('click', clickHandler);
}
element.addEventListener('click', clickHandler);