---

JS File Downloader

🌟Please remember to star this github repo if you like it. Thank you! ❤️

Introduction

JS File Downloader is a simple no dependency library you will be able to download file from browser and show downloading status.

- Install
- Basic usage
- Options
- process, check download status
- onloadstart
- headers
- filename
- timeout
- autoStart
- forceDesktopMode
- withCredentials
- method, GET/POST/...
- nameCallback, custom at runtime
- contentType
- nativeFallbackOnError
- body, of the request
- contentTypeDetermination
- customFileSignatures
- abort, to stop pending downloading request

$3

JS File Downloader supports all browsers that are [ES5-compliant] (http://kangax.github.io/compat-table/es5/) (IE8 and below are not supported).

---

$3

With a package manager (recommended):
``js
npm install js-file-downloader --save
`

$3

`js

import JsFileDownloader from 'js-file-downloader';

const fileUrl = 'http://...';

new JsFileDownloader({
url: fileUrl
})
.then(function () {
// Called when download ended
})
.catch(function (error) {
// Called when an error occurred
});

`

---

$3


Download this library from https://github.com/AleeeKoi/js-file-downloader/releases
`js


`

---

$3

#### process (for checking download status)
A function to call every time a process event is called. Function receive an Event Object as input.

`js

function process (event) {
if (!event.lengthComputable) return; // guard
var downloadingPercentage = Math.floor(event.loaded / event.total * 100);
// what to do ...
};

new JsFileDownloader({
url: '...',
process: process
})

`

#### onloadstart ('loadstart' event listener)
A function to call when a 'loadstart' event is triggered.

`js

function onloadstart () {
// what to do ...
}

new JsFileDownloader({
url: '...',
onloadstart
})

`

#### headers (of request)
If you need to customize request header data you can pass an array of objects like following example:

`js
new JsFileDownloader({
url: '...',
headers: [
{ name: 'Authorization', value: 'Bearer ABC123...' }
]
})
`

#### filename
Setting this String you can force output file name

#### timeout (ms)
Integer value (default 40000) defining how much ms attend before stop download action.

#### autoStart
Boolean value (default true) to enable/disable automatically starting the download. When the value is true the constructor returns a Promise, however when it's set to false, the constructor doesn't return anything and the download can be started by calling the start() method on the object.

Example with autoStart set to true
`js
new JsFileDownloader({
url: '...',
autoStart: true
})
`

Example with autoStart set to false
`js
const download = new JsFileDownloader({
url: '...',
autoStart: false
});

download.start()
.then(function(){
// success
})
.catch(function(error){
// handle errors
});
`

#### forceDesktopMode
Boolean value (default false) to force desktop mode even on mobile devices for downloading files.
`js
new JsFileDownloader({
url: '...',
forceDesktopMode: true
})
`

#### withCredentials
This is a Boolean that indicates whether or not cross-site Access-Control requests should be made using credentials such as cookies, authorization headers or TLS client certificates. Setting withCredentials has no effect on same-site requests.
`js
new JsFileDownloader({
url: '...',
withCredentials: true
})
`

#### method
The HTTP request method to use, such as "GET", "POST", "PUT", etc. (default "GET")
Ignored for non-HTTP(S) URLs.

`js
new JsFileDownloader({
url: '...',
method: 'POST'
})
`

#### nameCallback
You could pass a callback to customize final name, the function receive as 1st argument the name automatically extracted.

`js
new JsFileDownloader({
url: '...',
nameCallback: function(name) {
return 'i-am-prefix-' + name;
}
})
`

#### contentType
Setting this property you can customize the content type in the heade request, default is 'application/x-www-form-urlencoded'
If you set this property as false, the library doesn't set it.

`js
new JsFileDownloader({
url: '...',
contentType: 'multipart/form-data; boundary=something' // or false to unset it
})
`

---

#### nativeFallbackOnError
By setting this property to true (default is false) when error occours the download will fallback to the default behavior opening a new tab.

`js
new JsFileDownloader({
url: '...',
nativeFallbackOnError: true
})
`

---

#### body
By setting this property you can customize the body content sent with the request. Default value is null (nothing is sent), Document or BodyInit value can be set.

`js
new JsFileDownloader({
url: '...',
body: 'The body as a string'
})
`

#### contentTypeDetermination
By setting this property the downloader will determine the content type automatically depending on the value.

value | description
--- | ---
"header" | Gets type from content-type response header.
"signature" | Analyzes the first 4 bytes of the returned file and will check if that signature exists in the predetermined dict (You can override/merge this dict with the customFileSigantures property).
"full" | Uses both methods from above but prefers "siganture".
false | Type is not determined and the default is added, application/octet-stream.

`js
new JsFileDownloader({
url: '...',
contentTypeDetermination: 'header'
})
`

#### customFileSignatures
By setting this value you can override/merge the predefined signature dict (src/signatures.js). The key represents the hex code of a file (for more information here) and the value should be in the format of a content type (e.g. application/pdf). Setting this value has only an affect when contentTypeDetermination is set to "full" or "signature".

`js
new JsFileDownloader({
url: '...',
contentTypeDetermination: 'full', // must be set to "full" or "signature"
customFileSignatures: {
'FFFB':'audio/mpeg',
'FFF3':'audio/mpeg',
'FFF2':'audio/mpeg',
'494433': 'audio/mpeg'
}
})
`
___


$3


Setting autoStart option to false the process can be aborted calling the related method abort. The download promise is rejected, the reason can be customized passing is as the 1st param of the abort function.

`js
const download = new JsFileDownloader({
url: '...',
autoStart: false
});

download.start()
.catch(function(reason){
// handle errors
});

download.abort(/* reason /);

``
___

$3

MIT

Copyright (c) 2019-present, Alessandro Pellizzari

apedesign.net