Detect if a string is a data URL
Based on Brian Grinstead's solution https://gist.github.com/bgrins/6194623. Special thanks to Jamie Davis for helping to fix ReDoS exploit.
Syntax
The "data" URL scheme is described here RFC2397
dataurl := "data:" [ mediatype ] [ ";base64" ] "," data
mediatype := [ type "/" subtype ] *( ";" parameter )
data := *urlchar
parameter := attribute "=" value
where urlchar is imported from RFC2396, and type, subtype, attribute and value are the corresponding tokens from RFC2045, represented using URL escaped encoding of RFC2396 as necessary.
Attribute values in RFC2045 are allowed to be either represented as tokens or as quoted strings. However, within a data URL, the quoted-string representation would be awkward, since the quote mark is itself not a valid urlchar. For this reason, parameter values should use the URL Escaped encoding instead of quoted string if the parameter values contain any tspecial.
The ;base64 extension is distinguishable from a content-type parameter by the fact that it doesn't have a following = sign.
Install
npm install valid-data-url
Example
'use strict';
var validDataUrl = require('valid-data-url');
var isValid = validDataUrl('data:text/plain;base64,SGVsbG8sIFdvcmxkIQ%3D%3D'); // truePeople
The original author is Brian Grinstead
Contributors
Licence
The MIT License (MIT)
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