在javascript中将base64转换为blob
在javascript中将base64转换为blob
提问于 2015-01-16 17:17:17
在iOS 8上运行的Cordova/混合应用程序上，我尝试使用以下函数b64toBlob将JPEG的base64字符串转换为blob。
b64toBlob = function(b64, onsuccess, onerror) {
var img = new Image();
img.onerror = onerror;
img.onload = function onload() {
var canvas = document.createElement('canvas');
canvas.width = img.width;
canvas.height = img.height;
var ctx = canvas.getContext('2d');
ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
canvas.toBlob(onsuccess);
};
img.src = b64;
}但是它给出了一个错误
Uncaught Error: TypeError: undefined is not a function (evaluating 'canvas.toBlob(onsuccess)')当我们这样做的时候
var imageData = "data:image/jpeg;base64," + imageData
b64toBlob(imageData,
function(imageBlob) {
uploadBlob(imageBlob)
}, function(error) {
console.log(error)
});如何解决此错误？
回答 4
Stack Overflow用户
回答已采纳
发布于 2015-01-16 17:29:34
试试这个。请注意，假设dataURI包含base64前缀。(例如"data:image/jpeg;base64,")
function b64toBlob(dataURI) {
var byteString = atob(dataURI.split(',')[1]);
var ab = new ArrayBuffer(byteString.length);
var ia = new Uint8Array(ab);
for (var i = 0; i < byteString.length; i++) {
ia[i] = byteString.charCodeAt(i);
}
return new Blob([ab], { type: 'image/jpeg' });
}用法：
...
var blob = b64toBlob(imageData);
var formData = new FormData();
formData.append("source", blob);
...Stack Overflow用户
发布于 2018-07-05 03:33:45
简而言之，您可以使用以下函数，但如果您想了解更多详细信息，可以阅读这篇文章Create a blob from base64 data
const b64toBlob = (b64Data, contentType='', sliceSize=512) => {
const byteCharacters = atob(b64Data);
const byteArrays = [];
for (let offset = 0; offset < byteCharacters.length; offset += sliceSize) {
const slice = byteCharacters.slice(offset, offset + sliceSize);
const byteNumbers = new Array(slice.length);
for (let i = 0; i < slice.length; i++) {
byteNumbers[i] = slice.charCodeAt(i);
}
const byteArray = new Uint8Array(byteNumbers);
byteArrays.push(byteArray);
}
const blob = new Blob(byteArrays, {type: contentType});
return blob;
}
Stack Overflow用户
发布于 2020-07-06 03:27:43
fetch("data:image/jpeg;base64," + base64Data)
.then(res => res.blob())
.then(blob => {
console.log(blob);
var url = window.URL.createObjectURL(blob);
});页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/27980612
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