使用 Swal 时,如何在 then 语句中获取 fetch async 的值?

How can I get the value of fetch async in then statement when I am using Swal?

这是我的源代码。我正在使用 sweetalert2.all.min.js 来使用 swal 弹出窗口。现在我有一个问题,如何从 then 语句中的 API 端点访问返回值?我也在源代码中标记了它。 这是来源:

Swal.fire({
        title: 'Welcome',
        text: "Enter Username and Password",
        html:
            '<input id="username_input" class="swal2-input" placeholder="Enter Username">',
        input: 'password',
        inputPlaceholder: 'Enter Password',
        inputAttributes: {
            autocapitalize: 'off'
        },
        showCancelButton: false,
        confirmButtonText: 'Login',
        showLoaderOnConfirm: true,
        preConfirm: (passwordEntered) => {
            var usernameEntered = document.getElementById('username_input').value;
            return fetch("...my_endpoint.../checkusername/" + usernameEntered + "/" + passwordEntered)
                .then(response => {
                    response.text().then((val) => {
                        return val   // **: I need to get this value in * place
                    });
                })
                .catch(error => {
                    return "ERROR";
                })
        },
        allowOutsideClick: () => {
            !Swal.isLoading()
        }
    }).then((result) => {
        alert(result.value);  // *: I need to access the value from **
    })

所以,当我记录结果值时,我得到 passwordEntered 变量的值。

通过删除 .then() 语法并切换到 async/await :

preConfirm: async (passwordEntered) => {
    var usernameEntered = document.getElementById('username_input').value;

    const response = await fetch("...my_endpoint.../checkusername/" + usernameEntered + "/" + passwordEntered);
    return await response.text();
},