React中用Fetch向Google Apps Script POST数据遇CORS问题求助

我是编程新手，已查阅资料一整天，但仍无法解决问题，恳请帮助。我尝试将React项目中的对象数据POST到Google Apps Script。

Apps Script代码 #

var ss = SpreadsheetApp.getActiveSpreadsheet(),
Rcm = ss.getSheetByName("Rcm"); // "Rcm"是工作表名称

function doPost(e) {
var para = e.parameter, 
method = para.method;

if (method == "write") {
write_data(para);
}

}

function write_data(para) {
var name = para.name,
email = para.email,
wechat = para.wechat;
degree = para.degree;
program = para.program;
Rcm.appendRow([name, email, wechat ,degree ,program]); 
}

React组件代码 #

在React中，我有一组合并后的对象数据：

const contactAll = {
        ...contact, 
        ...{name}, 
        ...{pronoun}, 
        ...{degree}, 
        ...{program}, 
        ...{recommender},
        ...{position},
        ...{organisation},
        ...{profession},
        ...{wording},
        ...{relationship},
        ...{recommend}
    };

我编写了向Google Apps Script发送POST请求的代码，为解决CORS问题将Content-Type从application/json改为text/plain，但仍出现错误：

let uri = "https://script.google.com/macros/s/AKfyc....gEOkUE8S42eZ_k5CGVAUQXw/exec";

    const navigate = useNavigate();

    const handleFetch = ( uri , data ) => {fetch( uri , {
        method: "Post",
        headers: { "Content-Type": "text/plain" },
        body: JSON.stringify( data )
    }).then(
        ()=>{
            console.log("data added");
        }).catch((error)=>{
            console.error('Error:', error);
        })
    };


    const handleSecSubmit = (e) => {
        e.preventDefault();
        handleFetch( uri , contactAll );
        navigate("/final", { state: { contactAll } });
    }
   

控制台输出 #

出现三个错误：

Access to fetch at 'https://script.google.com/macros/s/AKfycbw...S42eZ_k5CGVAUQXw/exec' from origin 'http://localhost:3000' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

POST https://script.google.com/macros/s/AKfycbwpQ...E8S42eZ_k5CGVAUQXw/exec net::ERR_FAILED 200

Second.js:55 Error: TypeError: Failed to fetch
    at handleFetch (Second.js:47:1)
    at handleSecSubmit (Second.js:62:1)
    at HTMLUnknownElement.callCallback (react-dom.development.js:4164:1)
    at Object.invokeGuardedCallbackDev (react-dom.development.js:4213:1)
    at invokeGuardedCallback (react-dom.development.js:4277:1)
    at invokeGuardedCallbackAndCatchFirstError (react-dom.development.js:4291:1)
    at executeDispatch (react-dom.development.js:9041:1)
    at processDispatchQueueItemsInOrder (react-dom.development.js:9073:1)
    at processDispatchQueue (react-dom.development.js:9086:1)
    at dispatchEventsForPlugins (react-dom.development.js:9097:1)

疑问 #

请问我遗漏了什么？应该重点学习哪些知识？

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