Understanding of cross domain and how to solve cross domain problems

         If two addresses have the same agreement , Domain name or ip, And the port , Then we will say that these two addresses are from the same source , Browsers have a security policy for addresses of the same origin , That is to prohibit non homologous data operations dom,cookie And receiving ajax, So once there is cross domain , our ajax Cross domain errors will appear when receiving data . There are two solutions to this cross domain error reporting , One is cors Technical solutions , One is jsonp Technical solutions .
        cors The solution depends entirely on the back end ( Personally, I am right nodejs There is also some research , Don't say it if you don't learn well ),cors Back end personnel can directly configure , At present commonly used ajax Version pair cors The technical support is very good , We can call the interface directly at the front end , The back end will use this technology to solve cross domain .
         and jsonp There's a little bit of trouble , It looks like ajax request , He is a use script A technology of tag sending request , He is front and back , The data returned from the back end to the front end is not simply an object , It's a call to execute a function , Pass the data to be returned as parameters to the parameters of the executing function . Then it requires that the front end must prepare a global callback function to accept this data , When the program is finished , Function will be destroyed ,script Labels will also be destroyed ,jsonp It is compatible with lower version browsers . The disadvantage is that you can only send get request .