实现div鼠标拖动

//获取元素
	var dv = document.getElementById('show-result');
	var x = 0;
	var y = 0;
	var l = 0;
	var t = 0;
	var isDown = false;
	//鼠标按下事件
	dv.onmousedown = function(e) {
		//获取x坐标和y坐标
		x = e.clientX;
		y = e.clientY;

		//获取左部和顶部的偏移量
		l = dv.offsetLeft;
		t = dv.offsetTop;
		//开关打开
		isDown = true;
		//设置样式  
		dv.style.cursor = 'move';
	}
	//鼠标移动
	window.onmousemove = function(e) {
		if (isDown == false) {
			return;
		}
		//获取x和y
		var nx = e.clientX;
		var ny = e.clientY;
		//计算移动后的左偏移量和顶部的偏移量
		var nl = nx - (x - l);
		var nt = ny - (y - t);

		dv.style.left = nl + 'px';
		dv.style.top = nt + 'px';
	}
	//鼠标抬起事件
	dv.onmouseup = function() {
		//开关关闭
		isDown = false;
		dv.style.cursor = 'default';
	}