通过添加扩展上述解决方案，并在需要的地方添加用例 能够遍历表单上的多个字段并获取它们的值 其中一个是文件，它导致了异步需求的问题

解决方法如下:

    async collectFormData() {
        // Create the file parsing promise
        const toBase64 = file => new Promise((resolve, reject) => {
            const reader = new FileReader();
            reader.readAsDataURL(file);
            reader.onload = () => resolve(reader.result);
            reader.onerror = error => reject(error);
        });
    
        
        let form_vals = []
        let els = [] // Form elements collection

        // This is separate because wrapping the await in a callback
        // doesn't work 
        $(`.form-field`).each(function (e) {
            els.push(this) // add to the collection of form fields
        })

        // Loop through the fields to collect information 
        for (let elKey in els) {
            let el = els[elKey]

            // If the field is input of type file. call the base64 parser
            if ($(el).attr('type') == 'file') {
                // Get a reference to the file
                const file = el.files[0];

                form_vals.push({
                    "key": el.id,
                    "value": await toBase64(file)
                })

        }


        // TODO: The rest of your code here form_vals will now be 
        // populated in time for a server post
    }

这纯粹是为了解决处理多个字段的问题 以一种更流畅的方式

如果你在寻找一个基于承诺的解决方案，这是@Dmitri的代码适应:

function getBase64(file) {
  return new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.readAsDataURL(file);
    reader.onload = () => resolve(reader.result);
    reader.onerror = error => reject(error);
  });
}

var file = document.querySelector('#files > input[type="file"]').files[0];
getBase64(file).then(
  data => console.log(data)
);

我用过这个简单的方法，而且效果很好

 function  uploadImage(e) {
  var file = e.target.files[0];
    let reader = new FileReader();
    reader.onload = (e) => {
    let image = e.target.result;
    console.log(image);
    };
  reader.readAsDataURL(file);
  
}

这是

// fileObj: File
const base64 = window.URL.createObjectURL(fileObj);

// You can use it with <img src={base64} />

打印稿版本

const file2Base64 = (file:File):Promise<string> => {
    return new Promise<string> ((resolve,reject)=> {
         const reader = new FileReader();
         reader.readAsDataURL(file);
         reader.onload = () => resolve(reader.result?.toString() || '');
         reader.onerror = error => reject(error);
     })
    }

通过添加扩展上述解决方案，并在需要的地方添加用例 能够遍历表单上的多个字段并获取它们的值 其中一个是文件，它导致了异步需求的问题

解决方法如下:

    async collectFormData() {
        // Create the file parsing promise
        const toBase64 = file => new Promise((resolve, reject) => {
            const reader = new FileReader();
            reader.readAsDataURL(file);
            reader.onload = () => resolve(reader.result);
            reader.onerror = error => reject(error);
        });
    
        
        let form_vals = []
        let els = [] // Form elements collection

        // This is separate because wrapping the await in a callback
        // doesn't work 
        $(`.form-field`).each(function (e) {
            els.push(this) // add to the collection of form fields
        })

        // Loop through the fields to collect information 
        for (let elKey in els) {
            let el = els[elKey]

            // If the field is input of type file. call the base64 parser
            if ($(el).attr('type') == 'file') {
                // Get a reference to the file
                const file = el.files[0];

                form_vals.push({
                    "key": el.id,
                    "value": await toBase64(file)
                })

        }


        // TODO: The rest of your code here form_vals will now be 
        // populated in time for a server post
    }

这纯粹是为了解决处理多个字段的问题 以一种更流畅的方式