我可以在浏览器中检测到async / await吗？

与任何其他语法特征一样，应对其进行评估以便进行检测。由于可以限制 eval ，因此在启用CSP时可能无法实现此目的：

As any other syntactic feature, it should be evaluated in order to be detected. Since eval can be restricted, this may be impossible when CSP is enabled:

let isAsync = true;

try {
  eval('async () => {}');
} catch (e) {
  if (e instanceof SyntaxError)
    isAsync = false;
  else
    throw e; // throws CSP error
}

如果目标浏览器有可能不支持一个功能，代码应该被转换。

If there's a chance that target browsers don't support a feature, the code should be transpiled.

允许避免对 eval 的CSP限制的替代方法是使用用于检测语法功能的外部脚本，如此处所述。

The alternative that allows to avoid CSP restrictions on eval is to use external script to detect syntactic features, as described here.