JavaScript code to be evaluated  `window.location.href`
function () {
                    var js, index = parserInput.i;

                    parserInput.save();

                    var escape = parserInput.$char('~');
                    var jsQuote = parserInput.$char('`');

                    if (!jsQuote) {
                        parserInput.restore();
                        return;
                    }

                    js = parserInput.$re(/^[^`]*`/);
                    if (js) {
                        parserInput.forget();
                        return new(tree.JavaScript)(js.substr(0, js.length - 1), Boolean(escape), index, fileInfo);
                    }
                    parserInput.restore('invalid javascript definition');
                }