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Omar Khalil
2,769 Pointswhat is the point of creating the callback function before sending the request?
The structure of an ajax request is: create an XMLhttp object > create a call back function > open a request > send a request
why can't it be like this : create an XMLhttp object > open a request > send a request> create a call back function
what is the point of creating the callback function before sending the request?
2 Answers
Steven Parker
229,732 PointsThe callback must be associated with the XHR before you perform any operations on it, because it will be needed to handle state change events. Since these events can happen at any time, your callback must be ready for them.
Omar Khalil
2,769 PointsWell, somehow yes thanks
Omar Khalil
2,769 PointsOmar Khalil
2,769 Pointswith all respect, but your answer doesn't answer the question at all.
thanks anyway
Steven Parker
229,732 PointsSteven Parker
229,732 PointsMaybe a simile would convey the point better:
Creating the callback after sending the request would be like buying fire insurance after your house burns down.
Just like insurance, the callback must already be there to handle the events that will happen at times you cannot predict.
Does that clarify the answer?