The type
property of a Blob
object returns the MIME type of the file.
A string containing the file's MIME type, or an empty string if the type could not be determined.
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.
html
<input type="file" id="input" multiple /> <output id="output">Choose image files…</output>
js
// Our application only allows GIF, PNG, and JPEG images const allowedFileTypes = ["image/png", "image/jpeg", "image/gif"]; const input = document.getElementById("input"); const output = document.getElementById("output"); input.addEventListener("change", (event) => { const files = event.target.files; if (files.length === 0) { output.innerText = "Choose image files…"; return; } const allAllowed = Array.from(files).every((file) => allowedFileTypes.includes(file.type), ); output.innerText = allAllowed ? "All files clear!" : "Please choose image files only."; });
Specification |
---|
File API # dfn-type |
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
type |
5 | 12 | 4 | 10 | 11 | 6 | 4.4 | 18 | 4 | 11 | 6 | 1.0 |
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https://developer.mozilla.org/en-US/docs/Web/API/Blob/type