The download() function is used to trigger a file download from JavaScript. It specifies the contents and name of a new file placed in the browser's download directory. The input can be a String, Blob, or Typed Array of data, or via a dataURL representing the file's data as base64 or url-encoded string. No matter the input format, download() saves a file using the specified file name and mime information in the same manner as a server using a Content-Disposition HTTP header.
npm install downloadjs
bower install downloadjs
require("downloadjs")(data, strFileName, strMimeType);
download(data, strFileName, strMimeType);
require(['path/to/file'], function(download) {
download(data, strFileName, strMimeType);
});
- data - The Blob, File, String, or dataURL containing the soon-to-be File's contents.
- strFileName - The name of the file to be created. Note that older browsers (like FF3.5, Ch5) don't honor the file name you provide, instead they automatically name the downloaded file.
- strMimeType - The MIME content-type of the file to download. While optional, it helps the browser present friendlier information about the download to the user, encouraging them to accept the download.
text string - live demo
download("hello world", "dlText.txt", "text/plain");
text dataURL - live demo
download("data:text/plain,hello%20world", "dlDataUrlText.txt", "text/plain");
text blob - live demo
download(new Blob(["hello world"]), "dlTextBlob.txt", "text/plain");
text UInt8 Array - live demo
var str= "hello world", arr= new Uint8Array(str.length);
str.split("").forEach(function(a,b){
arr[b]=a.charCodeAt();
});
download( arr, "textUInt8Array.txt", "text/plain" );
html string - live demo
download(document.body.outerHTML, "dlHTML.html", "text/html");
html Blob - live demo
download(new Blob(["hello world".bold()]), "dlHtmlBlob.html", "text/html");
ajax callback - live demo
$.ajax({
url: "/download.html",
success: download.bind(true, "text/html", "dlAjaxCallback.html")
});
download.js works with a wide range of devices and browsers.
You can expect it to work for the vast majority of your users, with some common-sense limits:
- Devices without file systems like iPhone, iPad, Wii, et al. have nowhere to save the file to, sorry.
- Android support starts at 4.2 for the built-in browser, though chrome 36+ and firefox 20+ on android 2.3+ work well.
- Devices without Blob support won't be able to download Blobs or TypedArrays
- Legacy devices (no a[download]) support can only download a few hundred kilobytes of data, and can't give the file a custom name.
- Devices without window.URL support can only download a couple megabytes of data
- IE versions of 9 and before are NOT supported because the don't support a[download] or dataURL frame locations.
- 2008 :: landed a FF+Chrome compat way of downloading strings to local un-named files, upgraded to use a hidden frame and optional mime
- 2012 :: added named files via a[download], msSaveBlob() for IE (10+) support, and window.URL support for larger+faster saves than dataURLs
- 2014 :: added dataURL and Blob Input, bind-toggle arity, and legacy dataURL fallback was improved with force-download mime and base64 support
- 2015 :: converted to amd/commonJS module with browser-friendly fallback
- 20XX :: ???? Considering Zip, Tar, and other multi-file outputs, Blob.prototype.download option, and more, stay tuned folks.