dynamic change utterances theme with coder theme (#676)

Zhan Shuo

29.38.2022 9ea82c5c8247d4dd220e7441be645acc00e8cf29

 assets/js/coder.js

@@ -34,6 +34,48 @@
    body.classList.remove('colorscheme-' + inverse);
    body.classList.add('colorscheme-' + theme);
    document.documentElement.style['color-scheme'] = theme;

    function waitForElm(selector) {
        return new Promise(resolve => {
            if (document.querySelector(selector)) {
                return resolve(document.querySelector(selector));
            }
    
            const observer = new MutationObserver(mutations => {
                if (document.querySelector(selector)) {
                    resolve(document.querySelector(selector));
                    observer.disconnect();
                }
            });

            observer.observe(document.body, {
                childList: true,
                subtree: true
            });
        });
    }

    if (theme === 'dark') {
        const message = {
            type: 'set-theme',
            theme: 'github-dark'
        };
        waitForElm('.utterances-frame').then((iframe) => {
            iframe.contentWindow.postMessage(message, 'https://utteranc.es');
        })
        
    }
    else {
        const message = {
            type: 'set-theme',
            theme: 'github-light'
        };
        waitForElm('.utterances-frame').then((iframe) => {
            iframe.contentWindow.postMessage(message, 'https://utteranc.es');
        })
        
    }
    
}

function rememberTheme(theme) {