MJS
text/javascript
Magic Bytes
Offset: 0
2F 2A 20 6A 51 75 65 72 79 20
MJS files represent ECMAScript Modules, a JavaScript source code format standardized by ECMA International and utilized primarily within the Node.js runtime environment. These files enable strict modularity in applications, allowing developers to explicitly separate code scope using native import and export statements distinct from legacy CommonJS. While standard text-based source code is inherently safe to view, these scripts execute arbitrary logic and should be reviewed before running in privileged environments.
Validation Code
How to validate .mjs files in Python
Python
def is_mjs(file_path: str) -> bool:
"""Check if file is a valid MJS by magic bytes."""
signature = bytes([0x2F, 0x2A, 0x20, 0x6A, 0x51, 0x75, 0x65, 0x72, 0x79, 0x20])
with open(file_path, "rb") as f:
return f.read(10) == signatureHow to validate .mjs files in Node.js
Node.js
function isMJS(buffer: Buffer): boolean {
const signature = Buffer.from([0x2F, 0x2A, 0x20, 0x6A, 0x51, 0x75, 0x65, 0x72, 0x79, 0x20]);
return buffer.subarray(0, 10).equals(signature);
}
Go
func IsMJS(data []byte) bool {
signature := []byte{0x2F, 0x2A, 0x20, 0x6A, 0x51, 0x75, 0x65, 0x72, 0x79, 0x20}
if len(data) < 10 {
return false
}
return bytes.Equal(data[:10], signature)
}API Endpoint
GET
/api/v1/mjs
curl https://filesignature.org/api/v1/mjs