Javascript-我从一个字符串创建了一个 blob，如何将字符串返回？

我在一个字符串上调用 Blob () :

var mystring = "Hello World!";
var myblob = new Blob([mystring], {
type: 'text/plain'
});
mystring = "";

我怎么把绳子拉出来？

function getBlobData(blob) {
// Not sure what code to put here
}
alert(getBlobData(myblob)); // should alert "Hello World!"

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最佳答案

In order to extract data from a Blob, you need a FileReader.

var reader = new FileReader();
reader.onload = function() {
alert(reader.result);
}
reader.readAsText(blob);

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If the browser supports it, you could go via a blob URI and XMLHttpRequest it

function blobToString(b) {
var u, x;
u = URL.createObjectURL(b);
x = new XMLHttpRequest();
x.open('GET', u, false); // although sync, you're not fetching over internet
x.send();
URL.revokeObjectURL(u);
return x.responseText;
}

Then

var b = new Blob(['hello world']);
blobToString(b); // "hello world"

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@joey asked how to wrap @philipp's answer in a function, so here's a solution that does that in modern Javascript (thanks @Endless):

const text = await new Response(blob).text()

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Try:

var mystring = "Hello World!";
var myblob = new Blob([mystring], {
type: 'text/plain'
});
mystring = "";
outurl = URL.createObjectURL(myblob);
fetch(outurl)
.then(res => res.text())
.then(data => {
console.log(data)
})


//'Hello World'

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You could use the blob.text() method.

blob.text().then(text => {
let blobText = text
})

It will return the content of the blob in UTF-8 encoding. Note that it has to be in an async.