本文实例讲述了JS实现利用闭包判断Dom元素和滚动条的方向。分享给大家供大家参考，具体如下：
一、判断滚动条的方向，利用闭包首先保存滚动条的位置，然后当滚动时候不断更新滚动初始值，然后通过差指判断方向
function scroll(fn) {
//利用闭包判断滚动条滚动的方向
var beforeScrollTop = document.body.scrollTop,
fn = fn || function() {};
window.addEventListener("scroll", function() {
var afterScrollTop = document.body.scrollTop,
delta = afterScrollTop - beforeScrollTop;
if (delta === 0) return false;
fn(delta > 0 "down" : "up");
beforeScrollTop = afterScrollTop;
}, false);
}
scroll(function(direction) { console.log(direction) });
二、判断鼠标的移动方向
function direction() {
var lastX = null,
lastY = null;
window.addEventListener("mousemove", function(event) {
var curX = event.clientX,
curY = event.clientY,
direction = '';
// console.info(event);
// console.info(event.clientX);
// console.info(event.clientY);
// 初始化坐标
if (lastX == null || lastY == null) {
lastX = curX;
lastY = curY;
return;
}
if (curX > lastX) {
direction += 'X右,';
} else if (curX < lastX) {
direction += 'X左,';
}
if (curY > lastY) {
direction += 'Y下';
} else if (curY < lastY) {
direction += 'Y上';
}
lastX = curX;
lastY = curY;
//console.info(direction);
document.getElementById("test").innerText = direction;
})
}
三、判断鼠标进入和出去某Dom元素的方式，这种没有利用闭包原理
var gaga = function(wrap) {
var wrap = document.getElementById(wrap);
var hoverDir = function(e) {
var w = wrap.offsetWidth,
h = wrap.offsetHeight,
x = (e.clientX - wrap.offsetLeft - (w / 2)) * (w > h "_blank" href="//www.jb51.net/Special/85.htm">javascript面向对象入门教程》、《JavaScript错误与调试技巧总结》、《JavaScript数据结构与算法技巧总结》、《JavaScript遍历算法与技巧总结》及《JavaScript数学运算用法总结》
希望本文所述对大家JavaScript程序设计有所帮助。