1     <script>
2         var box = document.querySelector(‘.box1‘)
3         console.log(box.offsetWidth);
4         console.log(box.style.width);
5     </script>

1 .box {
2             width: 200px;
3             height: 200px;
4             background-color: pink;
5             position: absolute;
6             left: 100px;
7             top: 100px;
8         }

1     <div class="box"></div>
2     <script>
3         var box = document.querySelector(‘.box‘)
4         box.addEventListener(‘mousemove‘, function (e) {
5             var x = e.pageX - this.offsetLeft;
6             var y = e.pageY - this.offsetTop;
7             this.innerHTML = ‘x坐标是‘ + x + ‘y坐标是‘ + y;
8         })
9     </script>