Function createOrUpdateStyle

src/inject/dynamic-theme/index.ts:46–65

(className: string, root: ParentNode = document.head || document)

let staticStyleMap = new WeakMap<ParentNode, Map<string, HTMLStyleElement>>();

function createOrUpdateStyle(className: string, root: ParentNode = document.head || document): HTMLStyleElement {
    let element: HTMLStyleElement | null = root.querySelector(`.${className}`);
    if (!staticStyleMap.has(root)) {
        staticStyleMap.set(root, new Map());
    }
    const classMap = staticStyleMap.get(root)!;
    if (element) {
        classMap.set(className, element);
    } else if (classMap.has(className)) {
        element = classMap.get(className)!;
    } else {
        element = document.createElement('style');
        element.classList.add('darkreader');
        element.classList.add(className);
        element.media = 'screen';
        element.textContent = '';
        classMap.set(className, element);
    }
    return element;
}

/**
 * Note: This function is used only with MV2.