Blob: size property
Baseline Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.
Note: This feature is available in Web Workers.
The size read-only property of the Blob interface returns the size of the Blob or File in bytes.
Value
The number of bytes of data contained within the Blob (or Blob-based object, such as a File).
Examples
This example uses an <input> element of type file to ask the user for a group of files, then iterates over those files outputting their names and lengths in bytes.
HTML
html
<input type="file" id="input" multiple /> <output id="output">Choose files…</output> JavaScript
js
const input = document.getElementById("input"); const output = document.getElementById("output"); input.addEventListener("change", (event) => { output.innerText = ""; for (const file of event.target.files) { output.innerText += `${file.name} has a size of ${file.size} bytes.\n`; } }); Result
Specifications
| Specification |
|---|
| File API # dfn-size |