js基础拖拽效果

function drag(ele) {
  const config = {
    mark: 0,
    x: 0,
    y: 0,
    left: ele.offsetLeft,
    top: ele.offsetTop,
    newLeft: 0,
    newTop: 0,
  }

  ele.onmousedown = (e) => {
    config.mark = 1;
    config.x = e.clientX;
    config.y = e.clientY;
  }
  document.addEventListener('mousemove', (e) => {    
    if (!config.mark) {
      return;
    }
    ele.style.left = config.left + e.clientX - config.x + 'px';
    ele.style.top = config.top + e.clientY - config.y + 'px';
    // 记录新的 left 和 top 
    config.newLeft = config.left + e.clientX - config.x;
    config.newTop = config.top + e.clientY - config.y;
  });
  document.addEventListener('mouseup', (e) => {    
    if (config.mark) {
      config.left = config.newLeft;
      config.top = config.newTop;
    }
    config.mark = 0;
  });
}

const div = document.querySelector('div');
const p = document.querySelector('p');
drag(div);
drag(p);
/*
<div style="background: rgb(0, 0, 0);  100px; height: 100px; position: absolute;"></div>
<p style="background: rgb(155, 155, 155);  100px; height: 100px; position: absolute;"></p>
*/