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
});

这个代码片段可以将你的字符串、图像甚至视频文件转换为Base64字符串数据。

<input id="inputFileToLoad" type="file" onchange="encodeImageFileAsURL();" /> <div id="imgTest"></div> <script type='text/javascript'> function encodeImageFileAsURL() { var filesSelected = document.getElementById("inputFileToLoad").files; if (filesSelected.length > 0) { var fileToLoad = filesSelected[0]; var fileReader = new FileReader(); fileReader.onload = function(fileLoadedEvent) { var srcData = fileLoadedEvent.target.result; // <--- data: base64 var newImage = document.createElement('img'); newImage.src = srcData; document.getElementById("imgTest").innerHTML = newImage.outerHTML; alert("Converted Base64 version is " + document.getElementById("imgTest").innerHTML); console.log("Converted Base64 version is " + document.getElementById("imgTest").innerHTML); } fileReader.readAsDataURL(fileToLoad); } } </script>

这很简单。 只需调用函数并传递你的图像。 2>保存返回值并在任何需要的地方使用。

//call like this
const convertedFile = await imageToBase64(fileObj);
console.log("convertedFile",convertedFile);

//this is the required function

 async function  imageToBase64(image) {
 const reader = new FileReader();
 reader.readAsDataURL(image);
 const data= await new Promise((resolve, reject) => {

   reader.onload = () => resolve(reader.result);

   reader.onerror = error => reject(error);

  });
return data;
}

export default imageToBase64;

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 " >

基本上，如果你的形象是

<img id='Img1' src='someurl'>

然后你可以把它转换成

var c = document.createElement('canvas');
var img = document.getElementById('Img1');
c.height = img.naturalHeight;
c.width = img.naturalWidth;
var ctx = c.getContext('2d');

ctx.drawImage(img, 0, 0, c.width, c.height);
var base64String = c.toDataURL();

以下是我所做的:

// Author James Harrington 2014
function base64(file, callback){
  var coolFile = {};
  function readerOnload(e){
    var base64 = btoa(e.target.result);
    coolFile.base64 = base64;
    callback(coolFile)
  };

  var reader = new FileReader();
  reader.onload = readerOnload;

  var file = file[0].files[0];
  coolFile.filetype = file.type;
  coolFile.size = file.size;
  coolFile.filename = file.name;
  reader.readAsBinaryString(file);
}

下面是你如何使用它

base64( $('input[type="file"]'), function(data){
  console.log(data.base64)
})