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Alex Rivera
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With Express / Connect I can set up an middleware function in either of the formats: function(req, res, next) // first argument will be a request Or function(err, req, res, next) // first argument will be an error Stepping back from Express, Connect, to basic JavaScript: I don't understand is how this is possible to have an optional first argument ? How can express know that my function will accept an err object first? I thought to make this possible the structure would have to be like the following: function(req, res, next, err) Am I missing something basic here? Is it possible to query how many arguments a function is expecting? The middleware function is passed to express, so the arguments variable is not valid. although length is correct... I think I have figured it out, would be good to have confirmation to whether this is the case. Example below: var fn; fn = function (one, two) {}; console.log(fn.length); // 2 fn = function (one, two, three) {}; console.log(fn.length); // 3
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