Mouse click and Drag Instead of Horizontal Scroll bar( To view full content of child Div)

let mouseDown = false;
let startX, scrollLeft;
const slider = document.querySelector('.parent');

const startDragging = (e) => {
  mouseDown = true;
  startX = e.pageX - slider.offsetLeft;
  scrollLeft = slider.scrollLeft;
}

const stopDragging = (e) => {
  mouseDown = false;
}

const move = (e) => {
  e.preventDefault();
  if(!mouseDown) { return; }
  const x = e.pageX - slider.offsetLeft;
  const scroll = x - startX;
  slider.scrollLeft = scrollLeft - scroll;
}

// Add the event listeners
slider.addEventListener('mousemove', move, false);
slider.addEventListener('mousedown', startDragging, false);
slider.addEventListener('mouseup', stopDragging, false);
slider.addEventListener('mouseleave', stopDragging, false);

.parent{
  width:300px;
  border:5px solid red;
  overflow-x: hidden; 
  float:left;
}
.child{
  width:1000px;
  float:left;
  font-size:15px;
  font-family:arial;
  padding:10px;
  cursor: pointer;
}

<div class="parent">
    <div class="child">    
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    </div>
</div>