参考：vue实现可拖拽div

HTML

<div class="drag-box" v-drag id="drag" v-if="isShowDrag">
	<Button type="primary" @click.stop="isShowDrag = false">关闭</Button>
</div>

CSS

.drag-box {
	position:absolute;
	top: 100px;
	left:100px;
 	width:100px;
    height:100px;
    background: #fff;
    border-radius: 5px;
    box-shadow: 0 4px 12px rgba(0,0,0,.15);
}

JS

export default {
	data(){
		return {
			isShowDrag: false,
		}
	},
	//自定义指令
	directives: {
        drag: {
            // 指令的定义
            bind: function(el) {
                let oDiv = el;  // 获取当前元素
                oDiv.onmousedown = (e) => {
                    console.log('onmousedown')
                    // 算出鼠标相对元素的位置
                    let disX = e.clientX - oDiv.offsetLeft;
                    let disY = e.clientY - oDiv.offsetTop;

                    document.onmousemove = (e) => {
                        // 用鼠标的位置减去鼠标相对元素的位置，得到元素的位置
                        let left = e.clientX - disX;
                        let top = e.clientY - disY;

                        oDiv.style.left = left + 'px';
                        oDiv.style.top = top + 'px';
                        
                    };

                    document.onmouseup = (e) => {
                        document.onmousemove = null;
                        document.onmouseup = null;
                    }
                }
            }
        }
    },
}