blocks|key|1957548|text|因为这是javascript和动态的，所以您可以定义与File接口匹配的您自己的类，并使用它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1957549|我不得不用dropzone.js来做这件事，因为我想模拟一个文件上传，它可以在文件对象上工作。|1957550|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

Because this is javascript and dynamic you could define your own class that matches the File interface and use that instead.

I had to do just that with dropzone.js because I wanted to simulate a file upload and it works on File objects.

blocks|key|1744240|text|现在你可以了！|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1744241|​|1744242|var+parts+=+[
++new+Blob(['you+construct+a+file...'],+{type:+'text/plain'}),
++'+Same+way+as+you+do+with+blob',
++new+Uint16Array([33])
];

//+Construct+a+file
var+file+=+new+File(parts,+'sample.txt',+{
++++lastModified:+new+Date(0),+//+optional+-+default+=+now
++++type:+"overide/mimetype"+//+optional+-+default+=+''
});

var+fr+=+new+FileReader();

fr.onload+=+function(evt){
+++document.body.innerHTML+=+evt.target.result+%2B+" <a+href="%2BURL.createObjectURL(file)%2B"+download="+%2B+file.name+%2B+">Download+"+%2B+file.name+%2B+"</a> type:+"%2Bfile.type%2B" last+modified:+"%2B+file.lastModifiedDate
}

fr.readAsText(file);|code-block|syntax|javascript|1744243|1744244|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|N|8|@]|9|@]|A|$G|H]]|$1|I|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|P|8|@]|9|@]|A|$]]]|K|$]]

Now you can!

<div class="snippet" data-lang="js" data-hide="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>var parts = [
 new Blob(['you construct a file...'], {type: 'text/plain'}),
 ' Same way as you do with blob',
 new Uint16Array([33])
];

// Construct a file
var file = new File(parts, 'sample.txt', {
 lastModified: new Date(0), // optional - default = now
 type: "overide/mimetype" // optional - default = ''
});

var fr = new FileReader();

fr.onload = function(evt){
 document.body.innerHTML = evt.target.result + "&lt;br&gt;&lt;a href="+URL.createObjectURL(file)+" download=" + file.name + "&gt;Download " + file.name + "&lt;/a&gt;&lt;br&gt;type: "+file.type+"&lt;br&gt;last modified: "+ file.lastModifiedDate
}

fr.readAsText(file);</code></pre>
</div>
</div>

blocks|key|1957625|text|现在，所有主流浏览器都支持它：https://developer.mozilla.org/en-US/docs/Web/API/File/File|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1957626|var+file+=+new+File(["foo"],+"foo.txt",+{
++type:+"text/plain",
});|code-block|syntax|javascript|1957627|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/API/File/File^0|F|1M|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

Now it's possible and supported by all major browsers: <a href="https://developer.mozilla.org/en-US/docs/Web/API/File/File" rel="nofollow noreferrer">https://developer.mozilla.org/en-US/docs/Web/API/File/File</a>

<pre><code>var file = new File(["foo"], "foo.txt", {
 type: "text/plain",
});
</code></pre>

blocks|key|1744389|text|idea+...To在javaScript中为DOM中已经存在的图像创建一个文件对象：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1744390|<img+src="../img/Products/fijRKjhudDjiokDhg1524164151.jpg">

var+file+=+new+File(['fijRKjhudDjiokDhg1524164151'],
+++++++++++++++++++++'../img/Products/fijRKjhudDjiokDhg1524164151.jpg',+
+++++++++++++++++++++{type:'image/jpg'});

//+created+object+file
console.log(file);|code-block|syntax|javascript|1744391|不要那样做！...(但我还是这么做了)|1744392|->控制台给出一个类似于对象文件的结果：|1744393|File(0)+{name:+"fijRKjokDhgfsKtG1527053050.jpg",+lastModified:+1527053530715,+lastModifiedDate:+Wed+May+23+2018+07:32:10+GMT%2B0200+(Paris,+Madrid+(heure+d’été)),+webkitRelativePath:+"",+size:+0,+…}
lastModified:1527053530715
lastModifiedDate:Wed+May+23+2018+07:32:10+GMT%2B0200+(Paris,+Madrid+(heure+d’été))+{}
name:"fijRKjokDhgfsKtG1527053050.jpg"
size:0
type:"image/jpg"
webkitRelativePath:""__proto__:File|1744394|但是物体的大小是错误的..。|1744395|为什么我需要这样做？|1744396|例如，在产品更新期间重新传输已上载的图像表单，以及在更新期间添加的附加图像|1744397|entityMap^0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|W|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|10|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|11|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|12|8|@]|9|@]|A|$]]]|T|$]]

The idea ...To create a File object (api) in javaScript for images already present in the DOM :

<pre><code>&lt;img src="../img/Products/fijRKjhudDjiokDhg1524164151.jpg"&gt;

var file = new File(['fijRKjhudDjiokDhg1524164151'],
 '../img/Products/fijRKjhudDjiokDhg1524164151.jpg', 
 {type:'image/jpg'});

// created object file
console.log(file);
</code></pre>

Don't do that ! ... (but I did it anyway)

-> the console give a result similar as an Object File :

<pre><code>File(0) {name: "fijRKjokDhgfsKtG1527053050.jpg", lastModified: 1527053530715, lastModifiedDate: Wed May 23 2018 07:32:10 GMT+0200 (Paris, Madrid (heure d’été)), webkitRelativePath: "", size: 0, …}
lastModified:1527053530715
lastModifiedDate:Wed May 23 2018 07:32:10 GMT+0200 (Paris, Madrid (heure d’été)) {}
name:"fijRKjokDhgfsKtG1527053050.jpg"
size:0
type:"image/jpg"
webkitRelativePath:""__proto__:File
</code></pre>

But the size of the object is wrong ...

Why i need to do that ?

For example to retransmit
 an image form already uploaded, during a product update, along with additional images added during the update

There's a <a href="https://developer.mozilla.org/en/DOM/File" rel="noreferrer"><code>File</code></a> object in JavaScript. I want to instantiate one for testing purposes.

I have tried <code>new File()</code>, but I get an "Illegal constructor" error.

Is it possible to create a <code>File</code> object ?

<hr/>

File Object reference : <a href="https://developer.mozilla.org/en/DOM/File" rel="noreferrer">https://developer.mozilla.org/en/DOM/File</a>

How to instantiate a File object in JavaScript?

在JavaScript中有一个对象。出于测试目的，我想实例化一个。我已经尝试过new File()，但是我得到了一个“非法构造函数”的错误。可以创建一个File对象吗？文件对象引用：

问如何在JavaScript中实例化文件对象？
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