node_modules/@plotly/mapbox-gl/src/ui/anchor.js

// @flow

export type Anchor =
    | 'center'
    | 'top'
    | 'bottom'
    | 'left'
    | 'right'
    | 'top-left'
    | 'top-right'
    | 'bottom-left'
    | 'bottom-right';

export const anchorTranslate: {[_: Anchor]: string} = {
    'center': 'translate(-50%,-50%)',
    'top': 'translate(-50%,0)',
    'top-left': 'translate(0,0)',
    'top-right': 'translate(-100%,0)',
    'bottom': 'translate(-50%,-100%)',
    'bottom-left': 'translate(0,-100%)',
    'bottom-right': 'translate(-100%,-100%)',
    'left': 'translate(0,-50%)',
    'right': 'translate(-100%,-50%)'
};

export function applyAnchorClass(element: HTMLElement, anchor: Anchor, prefix: string) {
    const classList = element.classList;
    for (const key in anchorTranslate) {
        classList.remove(`mapboxgl-${prefix}-anchor-${key}`);
    }
    classList.add(`mapboxgl-${prefix}-anchor-${anchor}`);
}