JS
text/javascript
⚠️
High Risk Format
This file type can contain executable code. Always validate source and scan with antivirus before opening.
Magic Bytes
Offset: 0
2F 2A 20 6A 51 75 65 72 79 20
JavaScript is a text-based scripting language originally created by Netscape and standardized by ECMA International under the ECMAScript specification. It serves as a core technology for the World Wide Web, enabling interactive features, dynamic content manipulation, and server-side logic via environments like Node.js. Due to its executable nature, this format carries significant security risks, as malicious scripts can compromise browser sessions or execute unauthorized system commands.
Validation Code
How to validate .js files in Python
Python
def is_js(file_path: str) -> bool:
"""Check if file is a valid JS 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 .js files in Node.js
Node.js
function isJS(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 IsJS(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/js
curl https://filesignature.org/api/v1/js