How many parameters are too many in JavaScript?

Question

I came across the following question on StackOverflow: How many parameters are too many?

This got me thinking, is there a practical limit imposed on the number of parameters of a JS function?

 test(65536); // okay test(65537); // too many function test(n) { try { new Function(args(n), "return 42"); alert(n + " parameters are okay."); } catch (e) { console.log(e); alert(n + " parameters are too many."); } } function args(n) { var result = new Array(n); for (var i = 0; i < n; i++) result[i] = "x" + i; return result.join(","); } 

Turns out, JavaScript imposes a practical limit of 65536 parameters on functions.

However, what's interesting is that the error message says that the limit is 65535 parameters:

SyntaxError: Too many parameters in function definition (only 65535 allowed)

So, I have two questions:

1. Why this discrepancy? Is it an off-by-one error in the language implementations?
2. Does the ECMAScript standard impose this limit on function parameters?

Answer 1

Argument length limited to 65536 https://bugs.webkit.org/show_bug.cgi?id=80797

There are different argument count limits, depending on how you test: http://mathiasbynens.be/demo/javascript-argument-count