marcoscaceres/MIMEType

MIMEType string parser

MIMEType

MIME Type string parser that tries to conform to the WHATWG MIME Sniff spec.

API

The MIMEType class consists of:

• constructor(string): takes a string representing a MIME type. This sends the string to the parser. If the string is non-conforming, it throws a TypeError errors.
• .essense property: the "type", "/", and "subtype" normalized to lower case. For example: "text/plain".
• .type: the primary type of the string. E.g., "application", "text", or "image".
• .subtype: The subtype. So, like, "plain" in "text/plain".
• .parameters: a Map consisting of the parameters that were passed, normalized per spec.
• .toString(): stringifier gives you back the MIME type in canonical form.

Exported utilty methods

• isValidMimeType(string) - returns boolean, checks if a MIME type is valid by parsing it.
• parseMimeType(string) - returns an object { type: string, subtype: string, params: object }.

Examples

Creating and parsing

// As a class
import { MIMEType } from "MIMEType";
// Or utility functions
import { isValidMimeType, parseMimeType } from "MIMEType";

const mimetype = new MIMEType("text/html; charset=UTF-8");

// This throws
try {
  new MIMEType("not valid");
} catch (err) {
  // nice try...
}

Accessing different parts

import { MIMEType } from "MIMEType";
const mimetype = new MIMEType("text/html; charset=UTF-8");
console.log(mimetype.essense); // text/html
console.log(mimetype.type) // text
console.log(mimetype.subtype) // html

Parameters

Parameters is just a regular JavaScript Map, so:

import { MIMEType } from "MIMEType";
const mimetype = new MIMEType("text/html; charset=UTF-8");

mimetype.parameters.has("charset"); // true

for(const [key, value] of mimetype.parameters) {
  console.log(key, value);
}