将curl命令转换为Ajax

I want to convert curl command :

curl -X POST -H "X-Requested-With: XMLHttpRequest" -H "Content-Type: application/json" -H "Cache-Control: no-cache" -d '{"username": "admin","password": "admin"}' "http://localhost:8080/api/auth/login"

to ajax jquery, i have tried to use this code below but it does not work:

$.ajax({
    type: 'POST',
    crossDomain: true,
    url: 'http://localhost:8080/api/auth/login',
    dataType : 'json',
    data: JSON.stringify(datax),
    success:function(data){
        console.log(data);
    },
    error: function(data) { // if error occured
        var responseText = $.parseJSON(data.responseText);
        if(responseText.error){

        }

    }
})
.done(function(data) {

})

dataType: 'json' does not reflects the contentType. It's for jQuery to know how to handle the answer.

You are looking for contentType...

$.ajax({
    type: 'POST',
    crossDomain: true,
    cache: false,
    url: 'http://localhost:8080/api/auth/login',
    contentType : 'application/json',
    data: JSON.stringify(datax) //Expecting datax is  username & password
})
.done(function(data) {
})

http://api.jquery.com/jquery.ajax/