How do I limit draggable area? it functions on top and left side, but not on the right side and bottom

Question

So I tried to block the draggable contents from overflowing the body.

It works on top and on the left side.

I can't limit the right side and bottom.

            e.pageX -= e.offsetX;
            e.pageY -= e.offsetY;

            // left/right constraint
            if (e.pageX - dragoffset.x < 0) {
                offsetX = 0;
            } else if (e.pageX + dragoffset.x > document.body.clientWidth) {
                offsetX = document.body.clientWidth - e.target.clientWidth;
            } else {
                offsetX = e.pageX - dragoffset.x;
            }

            // top/bottom constraint

            if (e.pageY - dragoffset.y < 0) {
                offsetY = 0;
            } else if (e.pageY + dragoffset.y > document.body.clientHeight) {
                offsetY = document.body.clientHeight - e.target.clientHeight;
            } else {
                offsetY = e.pageY - dragoffset.y;
            }   

            el.style.top = offsetY + "px";
            el.style.left = offsetX + "px";
        }
    });
};

Also, my divs are getting glitchy while I drag them around. They only stop on the right side and bottom when the text inside them is selected.

Answer 1

There is drag&drop library with feature to restrict movements of draggables

https://github.com/dragee/dragee

By default it restrict movements of element inside container. It take into account size of element.

import { Draggable } from 'dragee'
new Draggable(element, { container: document.body })

In same time it's possible to use custom bound function

import { Draggable, BoundToRectangle, Rectangle } from 'dragee'
new Draggable(element, { 
    bound: BoundToRectangle.bounding(Rectangle.fromElement(document.body, document.body))
})

where BoundToElement describe restrictions that you need

class BoundToRectangle {
  constructor(rectangle) {
    this.rectangle = rectangle
  }

  bound(point, size) {
    const calcPoint = point.clone()
    const rectP2 = this.rectangle.getP3()

    if (this.rectangle.position.x > calcPoint.x) {
      (calcPoint.x = this.rectangle.position.x)
    }
    if (this.rectangle.position.y > calcPoint.y) {
      calcPoint.y = this.rectangle.position.y
    }
    if (rectP2.x < calcPoint.x + size.x) {
      calcPoint.x = rectP2.x - size.x
    }
    if (rectP2.y < calcPoint.y + size.y) {
      calcPoint.y = rectP2.y - size.y
    }

    return calcPoint
  }
}

Size of element you can calculate next way:

let width = parseInt(window.getComputedStyle(element)['width'])
let height = parseInt(window.getComputedStyle(element)['height'])

I can also suggest to use translate3d property for movements instead of positions left and top, because it is more efficient