Blob.type - Web APIs 编辑

The type property of a Blob object returns the MIME type of the file.

Syntax

var mimetype = blob.type

Value

A DOMString containing the file's MIME type, or an empty string if the type could not be determined.

Example

This example asks the user to select a number of files, then checks each file to make sure it's one of a given set of image file types.

var i, fileInput, files, allowedFileTypes;

// fileInput is a HTMLInputElement: <input type="file" multiple id="myfileinput">
fileInput = document.getElementById("myfileinput");

// files is a FileList object (simliar to NodeList)
files = fileInput.files;

// our application only allows GIF, PNG, and JPEG images
allowedFileTypes = ["image/png", "image/jpeg", "image/gif"];

for (i = 0; i < files.length; i++) {
  // Test if file.type is an allowed file type.
  if (allowedFileTypes.indexOf(files[i].type) > -1) {
    // file type matched is one of allowed file types. Do something here.
  }
});

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Blob
• Using files from web applications