HTML <Input Type='File'> Apply a Filter

How to filter input type= file dialog by specific file type?

See http://www.w3schools.com/tags/att_input_accept.asp:

The accept attribute is supported in all major browsers, except
Internet Explorer and Safari. Definition and Usage

The accept attribute specifies the types of files that the server
accepts (that can be submitted through a file upload).

Note: The accept attribute can only be used with <input type="file">.

Tip: Do not use this attribute as a validation tool. File uploads
should be validated on the server.

Syntax <input accept="audio/*|video/*|image/*|MIME_type" />

Tip: To specify more than one value, separate the values with a comma
(e.g. <input accept="audio/*,video/*,image/*" />.

HTML input type='file' apply a filter

There is an "accept" attribute on file input controls, where you can specify the types of files you want. From what i'm seeing, though, many browsers like to ignore it -- the file types that can be specified are MIME types, so a strictly correct browser would have to look at every file regardless of extension and see if it's an image (and if so, what type it is).

Update: It seems at least some version of every major browser on Windows now provides at least some support for the accept attribute. (Even IE supports it, as of version 10.) However, it's still a bit early yet to rely on it, as IE 8 and 9 still don't support it. And support in general is a bit spotty.

• Chrome seems to have full support. It uses its own built-in list of types as well as the system's...so if either one defines the type, Chrome knows which files to show.
• IE 10 supports file extensions beautifully, and MIME types decently. It seems to use only the system's mapping of MIME type to extensions, though...which basically means if something on the user's computer didn't register those extensions with the right MIME types, IE won't show files of those MIME types.
• Opera only seems to support MIME types -- to the point where extensions actually disable the filter -- and the UI for the file selector sucks. You have to select a type in order to see the files of that type.
• Firefox appears to support only a limited set of types, and ignore other types as well as extensions.
• I don't have Safari, and don't plan on downloading it. If someone could document Safari's support... Partial support on safari. http://caniuse.com/#search=accept

You should consider adding the attribute, so browsers that support it can help the user find the right files more easily. But i would still suggest that you check the filename after the file's selected and show an error message if a file with the wrong extension is uploaded.

And of course, definitely have the server double-check that the file is the right type. File extensions are just a naming convention, and can be easily subverted. And even if we could trust the browser (which we can't), and even if it did attempt to filter stuff as you asked (which it might not), the chance of it actually verifying that that .doc file is truly a Word document is next to nil.

How to allow input type= file to accept only image files?

Use the accept attribute of the input tag. To accept only PNG's, JPEG's and GIF's you can use the following code:

<label>Your Image File
  <input type="file" name="myImage" accept="image/png, image/gif, image/jpeg" />
</label>

<input type="file" style="width:200px">

<input type="file" size="60" />

imgInp.onchange = evt => {
  const [file] = imgInp.files
  if (file) {
    blah.src = URL.createObjectURL(file)
  }
}

<form runat="server">
  <input accept="image/*" type='file' id="imgInp" />
  <img id="blah" src="#" alt="your image" />
</form>

<div class="form-group">
    <label for="file">Choose File</label>
    <input type="file"
           id="file"
           (change)="handleFileInput($event.target.files)">
</div>

fileToUpload: File | null = null;

handleFileInput(files: FileList) {
    this.fileToUpload = files.item(0);
}

uploadFileToActivity() {
    this.fileUploadService.postFile(this.fileToUpload).subscribe(data => {
      // do something, if upload success
      }, error => {
        console.log(error);
      });
  }

postFile(fileToUpload: File): Observable<boolean> {
    const endpoint = 'your-destination-url';
    const formData: FormData = new FormData();
    formData.append('fileKey', fileToUpload, fileToUpload.name);
    return this.httpClient
      .post(endpoint, formData, { headers: yourHeadersConfig })
      .map(() => { return true; })
      .catch((e) => this.handleError(e));
}