Friday, September 19, 2025
HomeLanguagesJavascriptJavaScript SyntaxError – Malformed formal parameter

JavaScript SyntaxError – Malformed formal parameter

This JavaScript exception malformed formal parameter occurs if the argument list of a Function() constructor call is not valid.

Message:

SyntaxError: Expected {x} (Edge)
SyntaxError: malformed formal parameter (Firefox)

Error Type:

SyntaxError

Cause of Error: The argument list passed to the function is not valid. The if or var can not be picked as an argument name, or there’s some stray punctuation in the argument list. The invalid value passed can cause a problem, like a number or an object.

Example 1: In this example, the number is used as an argument name. So the error has occurred.

Javascript




// error here
let f = Function(45, "alert('This is alert')");


Output(in console):

SyntaxError: Expected identifier

Example 2: In this example, there is a missing comma, So the error occurred.

Javascript




let f = Function('x y', 'return x + y;');


Output(in console):

SyntaxError: Expected ')'
Whether you’re preparing for your first job interview or aiming to upskill in this ever-evolving tech landscape, neveropen Courses are your key to success. We provide top-quality content at affordable prices, all geared towards accelerating your growth in a time-bound manner. Join the millions we’ve already empowered, and we’re here to do the same for you. Don’t miss out – check it out now!
RELATED ARTICLES

Most Popular

Dominic
32302 POSTS0 COMMENTS
Milvus
84 POSTS0 COMMENTS
Nango Kala
6666 POSTS0 COMMENTS
Nicole Veronica
11841 POSTS0 COMMENTS
Nokonwaba Nkukhwana
11898 POSTS0 COMMENTS
Shaida Kate Naidoo
6781 POSTS0 COMMENTS
Ted Musemwa
7056 POSTS0 COMMENTS
Thapelo Manthata
6739 POSTS0 COMMENTS
Umr Jansen
6745 POSTS0 COMMENTS