document.querySelector(“输入”)。Onchange = e => { const fr = new FileReader() Fr.onloadend = () => document.write(fr.result) fr.readAsDataURL (e.target.files [0]) ｝ < input type = " file " >

您可以使用FileAPI，但它几乎不受支持。

document.querySelector(“输入”)。Onchange = e => { const fr = new FileReader() Fr.onloadend = () => document.write(fr.result) fr.readAsDataURL (e.target.files [0]) ｝ < input type = " file " >

假设您在浏览器中执行此操作:

等待:

import axios from 'axios'

const response = await axios.get(url, { responseType: 'blob' });
return window.URL.createObjectURL(response.data);

与承诺

import axios from 'axios'

const response = await axios.get(url, { responseType: 'blob' })
  .then((response) => {
    const dataUrl = window.URL.createObjectURL(response.data);
    // do something with your url
  });

下面是使用Javascript Promise的方法。

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

现在，在事件处理程序中使用它。

const _changeImg = (e) => {
        const file = e.target.files[0];
        let encoded;
        getBase64(file)
          .then((result) => {
            encoded = result;
           })
          .catch(e => console.log(e))
    }

如果你有一个文件对象，这个简单的函数将工作:

function getBase64 (file, callback) {

    const reader = new FileReader();

    reader.addEventListener('load', () => callback(reader.result));

    reader.readAsDataURL(file);
}

使用的例子:

getBase64(fileObjectFromInput, function(base64Data){
    console.log("Base64 of file is", base64Data); // Here you can have your code which uses Base64 for its operation, // file to Base64 by oneshubh
});