javascript 附加 Blob 数据
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Appending Blob data
提问by Deni Spasovski
Is there a function for appending blob data in JavaScriptI currently use the following approach:
JavaScript我目前使用以下方法是否有附加 blob 数据的功能：
var bb = new Blob(["Hello world, 2"], { type: "text/plain" });
bb = new Blob([bb, ",another data"], { type: "text/plain" });
And BlobBuilderfunction is not available in Chrome.
并且BlobBuilder功能在 Chrome 中不可用。
回答by nkron
Blobs are "immutable" so you can't change one after making it. Constructing a new Blob that appends the data to an existing blob (as you wrote in your initial question) is a good solution.
Blob是“不可变的”，所以你不能在创建后改变它。构建一个将数据附加到现有 Blob 的新 Blob（如您在最初的问题中所写）是一个很好的解决方案。
If you don't need to use the Blob each time you append a part, you can just track an array of parts. Then you can continually append to the array and then construct the Blob at the end when you need it.
如果您不需要在每次附加零件时都使用 Blob，您可以只跟踪零件数组。然后你可以不断地追加到数组，然后在你需要的时候在最后构造 Blob。
var MyBlobBuilder = function() {
this.parts = [];
}
MyBlobBuilder.prototype.append = function(part) {
this.parts.push(part);
this.blob = undefined; // Invalidate the blob
};
MyBlobBuilder.prototype.getBlob = function() {
if (!this.blob) {
this.blob = new Blob(this.parts, { type: "text/plain" });
}
return this.blob;
};
var myBlobBuilder = new MyBlobBuilder();
myBlobBuilder.append("Hello world, 2");
// Other stuff ...
myBlobBuilder.append(",another data");
var bb = myBlobBuilder.getBlob();
