Node-rfc2397 NPM

node-rfc2397

NodeJS implementation of RFC 2397 (The "data" URL scheme), both parsing and composing.

Usage

`parse(dataurl, callback)`

Parse a RFC 2397 compliant string. callback is a function (err, info) that is called as callback(err) if an error arise and callback(null, info) on success. The info object yielded to callback has the following form:

{
    mime: "mime/type"     // the mime type (a string)
    parameters: {         // an object composed of the given dataurl parameters
        param1: "value1", // a string
        param2: "value2", // a string
        ...
    },
    data: // a Buffer constructed from the data part of the dataurl
}

Example:

var moddataurl = require("node-rfc2397");

// URL encoded
var dataurl = "data:text/plain;charset=cp866;foo=bar;answer=42,%e1%ab%ae%a2%ae";
moddataurl.parse(dataurl, function (err, info) {
    // err is null and info is the following object:
    // {
    //     mime: "text/plain",
    //     parameters: {
    //         charset: "cp866",
    //         foo: "bar",
    //         answer: "42",
    //     },
    //     data: <Buffer e1 ab ae a2 ae>,
    // }
});

// Base64
var dataurl = "data:text/plain;charset=utf-8;base64,SGVsbG8gV29ybGQh";
moddataurl.parse(dataurl, function (err, info) {
    // err is null and info is the following object:
    // {
    //    base64: true,
    //    mime: "text/plain",
    //    parameters: {
    //        charset: "utf-8"
    //    },
    //    data: <Buffer 48 65 6c 6c 6f 20 57 6f 72 6c 64 21>
    // }
    info.data.toString(); // "Hello World!"
});

`parseSync(dataurl)`

Synchronous version of parse(). This throws if an error occurs. dataurl is a RFC 2397 compliant string. Returns an info object, as described in the documentation of parse().

Example:

var moddataurl = require("node-rfc2397");

try {
    var dataurl = "data:text/plain;charset=utf-8,Hello%20World%21";
    var info = moddataurl.parseSync(dataurl)
    console.log(info);
    // {
    //     mime: 'text/plain',
    //     parameters: {
    //         charset: 'utf-8',
    //     },
    //     data: <Buffer 48 65 6c 6c 6f 20 57 6f 72 6c 64 21>
    // }

} catch (err) {
    console.log(err);
    throw err;
}

`compose(info, callback)`

Compose a RFC 2397 compliant string from the given object info. callback is a function (err, dataurl) that is called as callback(err) if an error arise and callback(null, dataurl) on success.

Example:

var moddataurl = require("node-rfc2397");

var info = {
    mime:"text/plain",
    parameters: {
        charset:"utf-8"
    },
    base64: true,
    data: Buffer.from("Hello World!")
};

moddataurl.compose(info, function (err, dataurl) {
    // err is null and dataurl is the following string:
    // "data:text/plain;charset=utf-8;base64,SGVsbG8gV29ybGQh"
});

`composeSync(info)`

Synchronous version of compose(). This throws if an error occurs. info is an object, as described in the documentation of compose(). Returns an RFC 2397 compliant string.

Example:

var moddataurl = require("node-rfc2397");

try {
    var info = {
        mime: "text/plain",
        parameters: {
            charset: "utf-8",
        },
        data: Buffer.from("Hello World!"),
    };
    var dataurl = moddataurl.composeSync(info);
    console.log(dataurl); // data:text/plain;charset=utf-8,Hello%20World%21
} catch (err) {
    console.log(err);
    throw err;
}

Implementation notes

The RFC 2397 is unfortunately vague regarding many details of the syntax of the data URL scheme. This node module does its best to have a solid implementation of the specification of the original RFC. However, some independent choices had to be made where the specification is unclear.

Duplicate parameter attribute handling

The RFC 2397 does not specify what needs to be done when duplicate parameter keys are encountered. The approach retained by this implementation is first given.

Example:

var moddataurl = require("node-rfc2397");
var info = moddataurl.parseSync("data:text/plain;foo=bar;foo=nope,");
console.log(info);
// {
//     mime: 'text/plain',
//     parameters: { foo: 'bar' },
//     data: <Buffer >,
// }