如果未使用javascript函数中的参数，会降低性能吗？

Question

I am using a plugin which monitors the dragging of an element. As the coordinates of the element change when it is dragged, several parameters are made available to an event listener function:

$el.on('dragMove',onDragMove);

onDragMove = function(e,pointer,vector){
  //
}

Is there any performance benefit to removing those parameters if I am not using them within the function:

onDragMove = function(){
  //
}

?

Answer 1

IMHO If there is any performance impact, you can ignore it. But for the syntax-sugar and code quality it is always better to define only what you need. Some code quality tools (JSLint for example) and editors will highlight it for you when you have parameters defined that you don't use inside the function.

Answer 2

There is minimal impact on performance due the low memory consumption of declaring the arguments as variables, since the Javascript plugin you are using is still sending to the arguments at those positions. Ultimately it would depend on the received data, as the function arguments, other than objects , are passed by value and not by reference.

The biggest benefit to removing the declarations, would be more so for readability of your code.