javascript 在javascript中将base64转换为blob
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Converting base64 to blob in javascript
提问by Nyxynyx
I tried to convert a JPEG's base64 string to a blob on a Cordova/hybrid app running on iOS 8 using the following function b64toBlob.
我尝试使用以下函数将 JPEG 的 base64 字符串转换为在 iOS 8 上运行的 Cordova/混合应用程序上的 blob b64toBlob。
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;
}
However it's giving an error
但是它给出了一个错误
Uncaught Error: TypeError: undefined is not a function (evaluating 'canvas.toBlob(onsuccess)')
when we do
当我们做
var imageData = "data:image/jpeg;base64," + imageData
b64toBlob(imageData,
function(imageBlob) {
uploadBlob(imageBlob)
}, function(error) {
console.log(error)
});
How can be work around this error?
如何解决此错误？
回答by filipvkovic
Try this out. Please note that dataURIis assumed to include base64 prefix. (ex: "data:image/jpeg;base64,")
试试这个。请注意，dataURI假定包含 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' });
}
Usage:
用法：
...
var blob = b64toBlob(imageData);
var formData = new FormData();
formData.append("source", blob);
...
回答by Mustafa Dwekat
In short, you can use the following function but if you want more details about this, you can read this post Create a blob from base64 data
简而言之，您可以使用以下功能，但如果您想了解更多有关此功能的详细信息，您可以阅读这篇文章从 base64 数据创建一个 blob
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;
}回答by YuXitong
I have the same problem. The reason for me is that there is space in the base64 string.base64Str = base64Str.replace(/\s/g, '')
我也有同样的问题。我的原因是base64字符串中有空格。base64Str = base64Str.replace(/\s/g, '')
This solved my problem
这解决了我的问题
回答by Gopala raja naika
Please try this simple way
请试试这个简单的方法
fetch(base64)
.then(res => {
return res.blob();
})
.then(blob => {
console.log(blob);
});
