Do unused paramenters in functions slow down the execution of JavaScript?

Question

Does having unused parameters in javascript functions slow down execution? Does it take up memory? I often write functions with parameters that are never actually used for example function has an event as a parameter, but the event is never used for anything.

Answer 1

slow down execution?

The running time depends upon the operation being performed on the input. May it be a search or a sort or any simple operation. The running time of the operation determines the speed of its execution. So when you don't pass any parameter, that means no action is being performed on that parameter and hence the running time is stable.

Does it take up memory?

But as far as memory allocation is concerned, they are generally allocated a Lexical Environment.

When the function runs, on every function call, the new LexicalEnvironment is created and populated with arguments, variables and nested function declarations.

So for the below function:

function sayHi(name) {
/* LexicalEnvironment = { name: passedvalue, 
                        phrase: undefined }*/  // created at this point.
  var phrase = "Hi, " + name
  alert(phrase)
}

So when you invoke it as sayHi(), the lexical envirmonemt looks like:

LexicalEnvironment = { name: undefined, phrase: undefined};

Hence, each parameters and function variables are allocated memory when the interpreter interprets the function.

When the interpreter is preparing to start function code execution, before the first line is run, an empty LexicalEnvironment is created and populated with arguments, local variables and nested functions.

Answer 2

JavaScript anyways stores parameters sent to every function in the arguments array, irrespective of you allocating local variables for them.

function test() {
    console.log(arguments)
}

test('these','are','passed')

//logs ["these','are',passed']

My point is that the unused parameters are anyways taking up memory, you are only referencing them using another variable name.