如何把它变成一个承诺？

I have this ajax call and I need to turn it into a promise.

function myRest(url, method, callback){
    return $.ajax({
        url : url,
        type : method,
        dataType: "json",
        contentType: "application/json",
        success: function(results){
            //things to do in case of success
                    },
        error: function (){
          //things to do in case of error           
}
    });
}

How could I also use the .then() method in case of success? Thanks

I have this ajax call and I need to turn it into a promise.

$.ajax() already returns a promise. You can just use .then() on it already, return the promise and get rid of the callback. You don't need to "turn anything into a promise". It already is a promise. You can use that existing promise like this:

function myRest(url, method) {
    return $.ajax({
        url : url,
        type : method,
        dataType: "json"
    });
}

myRest(...).then(function(results) {
    // success
}, function(jqXHR, textStatus, errorThrown) {
    // error
});