JS Syntax Reference (vs Python)

Ternary Operator

// JavaScript
let desc = format === 'csv' ? fileName : '';
//         condition          ? true value : false value

// Python
desc = file_name if format == 'csv' else ''

=== vs ==

Operator	Behavior	Recommendation
=== (strict)	Type AND value must match	JS convention — almost always use this
== (loose)	Auto-converts type before comparing	Avoid — easy to hit unexpected behavior

1 === '1'   // false (different types)
1 == '1'    // true  ('1' is coerced to number)
0 == ''     // true  😱
0 == false  // true  😱

Python's == doesn't auto-coerce types — this problem doesn't exist there.

null vs undefined

	null	undefined
Meaning	Intentionally set to "no value"	Undeclared / no value assigned
Python analogy	None	Variable simply doesn't exist

Commonly used as placeholders so positional arguments don't get misaligned:

sendRequest(command, userId, null, path, body, undefined);
//                            ^^^^                ^^^^^^^^^
//                            auth not needed      callback not needed