vue-select/src/directives/appendToBody.js

export default {
    inserted (el, bindings, {context}) {
        if (context.appendToBody) {
            const {height, top, left, width} = context.$refs.toggle.getBoundingClientRect();
            let scrollX = window.scrollX || window.pageXOffset;
            let scrollY = window.scrollY || window.pageYOffset;
            el.unbindPosition = context.calculatePosition(el, context, {
                width: width + 'px',
                left: (scrollX + left) + 'px',
                top: (scrollY + top + height) + 'px',
            });
            
            document.body.appendChild(el);
        }
    },

    unbind (el, bindings, {context}) {
        if (context.appendToBody) {
            if (el.unbindPosition && typeof el.unbindPosition === 'function') {
                el.unbindPosition();
            }
            if (el.parentNode) {
                el.parentNode.removeChild(el);
            }
        }
    },
}