How does node.js judge that a function defines several parameters

recently encountered a problem when learning node.js in action, while looking at the middleware section.
the book says

so how does connect determine how many parameters a function defines?

Front-end express connect node.js javascript

Mar.02,2021

< del > arguments.length < / del >

< hr >

sorry misread it. The number of parameters defined should be the length attribute of the function itself

arguments this parameter,
, and you can also take values in the order of the parameters, for example:

function test(a,b,c,d){}

call:

test(1,2,3);

then a corresponds to 1 code b corresponds to 2 meme c corresponds to 3, d is undefined

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