Webflags: gi

HTTP Content-Type Header

Parse the value of an HTTP Content-Type header, capturing the media type and optional charset.

Available in

JavaScript / ECMAScript code

jsJavaScript

const re = new RegExp("Content-Type:\\s*([a-z]+\\/[\\w.+\\-]+)(?:;\\s*charset=([\\w\\-]+))?", "gi");
const input = "Content-Type: text/html; charset=utf-8";
const matches = [...input.matchAll(re)];
console.log(matches.map(m => m[0]));

Uses `String.prototype.matchAll` for global iteration (Node 12+ / all modern browsers).

Python (re) code

pyPython

import re

pattern = re.compile(r"Content-Type:\s*([a-z]+\/[\w.+\-]+)(?:;\s*charset=([\w\-]+))?", re.IGNORECASE)
input_text = "Content-Type: text/html; charset=utf-8"
for m in pattern.finditer(input_text):
    print(m.group(0))

Stdlib `re` module — no third-party dependency. Works on Python 3.6+.

Go (RE2) code

goGo

package main

import (
	"fmt"
	"regexp"
)

func main() {
	re := regexp.MustCompile(`(?i)Content-Type:\s*([a-z]+\/[\w.+\-]+)(?:;\s*charset=([\w\-]+))?`)
	input := `Content-Type: text/html; charset=utf-8`
	for _, match := range re.FindAllString(input, -1) {
		fmt.Println(match)
	}
}

Uses `regexp.MustCompile` (panics on bad patterns at startup) and `FindAllString` for all matches.

Pattern

regexengine-agnostic

Content-Type:\s*([a-z]+\/[\w.+\-]+)(?:;\s*charset=([\w\-]+))?   (flags: gi)

Raw source: Content-Type:\s*([a-z]+\/[\w.+\-]+)(?:;\s*charset=([\w\-]+))?

How it works

Content-Type:\s* matches the header name and required whitespace. ([a-z]+\/[\w.+\-]+) captures the type/subtype (the i flag makes this case-insensitive). (?:;\s*charset=([\w\-]+))? optionally captures a charset parameter — UTF-8, iso-8859-1, etc.