JQuery Ajax Set Request header information Application/json

There's an API backstage in Application/json format today.
In jquery $.ajax default is contenttype:application/x-www-form-urlencoded; Charset=utf-8
This format is the form submission format, the data is K1=V1&K2=V2 format
Although you can set the {k1:v1,k2:v2} in data, it will be converted to k1=v1&k2=v2 at the time of submission.

So I added contenttype to the argument: ' Application/json;charset=utf-8 '.
But it's still an illegal request. 400
Finally, after a long time, I finally know why.
Data object needs to be converted to a JSON string

$.Ajax({  URL: ' Your URL ',  type: ' POST ',  DataType:"JSON",  ContentType: ' Application/json;charset=utf-8 ',  Data: JSON.stringify({ID: 1}),}). Done(function(data){  Console.Log(Data,"Success");})

This gives you a normal access to the

JQuery Ajax Set Request header information Application/json