Drag'n'drop Vue.js mixin to use with vue-drap-grop plugin to be able to use coordinates in Firefox

drag_drop.mixin.js

import $ from 'jquery';

export default {
    data () {
        return {
            initOffset: {
                x: 0,
                y: 0,
            },
            coordinates: {
                x: 0,
                y: 0,
            },
        };
    },
    computed: {
        shiftCoordinates() {
            return {
                x: this.coordinates.x - this.initOffset.x,
                y: this.coordinates.y - this.initOffset.y,
            }
        },
    },
    mounted () {
        // Dirty hack for Firefox only...
        // @ref: https://stackoverflow.com/questions/887316/how-do-i-get-clientx-and-clienty-to-work-inside-my-drag-event-handler-on-firef?rq=1
        $(document)
            .on('dragstart', (e) => {
                e = e.originalEvent;
                this.initOffset.x = e.clientX || e.pageX;
                this.initOffset.y = e.clientY || e.pageY;
            });

        $(document)
            .on('dragover', (e) => {
                e = e.originalEvent;
                this.coordinates.x = e.clientX || e.pageX;
                this.coordinates.y = e.clientY || e.pageY;
            });
    },
};