async/await demo

demo.js

    if(this.options && this.options.renderingConfig && this.options.renderingConfig.codeSyntaxHighlighting === true && window.Prism) {
        function autoLoadLanguage(lang) {
            return new Promise(resolve => {
                window.Prism.plugins.autoloader.loadLanguages([lang], function () {
                    console.log('+++ success auto-load', lang);
                    resolve('resolved');
                });
            });
        }

        markedOptions.highlight = async function(code, lang) {
            console.log('calling');
            const result = await autoLoadLanguage(lang);
            console.log(result);

            var grammar = window.Prism.languages[lang];
            if (grammar === undefined) {
                console.error("Undefined Prism.js grammar for", lang);
                return code;
            }
            return window.Prism.highlight(code, grammar, lang);
        };
    }