想用JS做炫酷的特效，你得先知道这些！！！

特效 （必备的一些知识点）

偏移量

• offsetParent用于获取定位的父级元素
• offsetParent和parentNode的区别

var box = document.getElementById('box');
console.log(box.offsetParent);
console.log(box.offsetLeft);
console.log(box.offsetTop);
console.log(box.offsetWidth);
console.log(box.offsetHeight);

客户区大小

var box = document.getElementById('box');
console.log(box.clientLeft);
console.log(box.clientTop);
console.log(box.clientWidth);
console.log(box.clientHeight);

滚动偏移

var box = document.getElementById('box');
console.log(box.scrollLeft)
console.log(box.scrollTop)
console.log(box.scrollWidth)
console.log(box.scrollHeight)