如何在Code.fromInline传入的动态代码中访问someVar变量？

因为Code.fromInline()接收的是字符串形式的代码，这段代码会在Edge Function的独立运行环境中执行，和外部定义的someVar不在同一个上下文，所以无法直接引用。你可以通过以下几种方式解决：

1. 模板字符串插值（适用于非敏感数据） #

直接通过模板字符串将外部变量的值注入到内联代码中：

const someVar = "some value";
const rewriteFunction = new cf.experimental.EdgeFunction(
    this,
    "RewriteFunction",
    {
        runtime: Runtime.NODEJS_18_X,
        handler: "index.handler",
        code: Code.fromInline(`
        exports.handler = async (event) => {
            const request = event.Records[0].cf.request;
            // 注入外部变量的值
            const injectedVar = "${someVar}";
            console.log(injectedVar); // 输出 "some value"
        };
        `),
    }
);

如果someVar是对象、数组等复杂类型，需要先转成JSON字符串，再在内部解析：

const someVar = { key: "value", num: 123 };
const rewriteFunction = new cf.experimental.EdgeFunction(
    this,
    "RewriteFunction",
    {
        runtime: Runtime.NODEJS_18_X,
        handler: "index.handler",
        code: Code.fromInline(`
        exports.handler = async (event) => {
            const request = event.Records[0].cf.request;
            const injectedVar = JSON.parse('${JSON.stringify(someVar)}');
            console.log(injectedVar.key); // 输出 "value"
        };
        `),
    }
);

2. 使用环境变量（适用于敏感数据） #

如果someVar包含敏感信息，建议通过Edge Function的环境变量配置传递，避免硬编码：

const someVar = "some sensitive value";
const rewriteFunction = new cf.experimental.EdgeFunction(
    this,
    "RewriteFunction",
    {
        runtime: Runtime.NODEJS_18_X,
        handler: "index.handler",
        code: Code.fromInline(`
        exports.handler = async (event) => {
            const request = event.Records[0].cf.request;
            // 从环境变量读取值
            const injectedVar = process.env.SOME_VAR;
            console.log(injectedVar);
        };
        `),
        // 配置环境变量
        environment: {
            variables: {
                SOME_VAR: someVar
            }
        }
    }
);

内容的提问来源于stack exchange，提问作者David Klempfner