<input id="clickMe" type="button" value="clickme" onclick="doFunction();" />
<script>

xmlhttp = new XMLHttpRequest();
var url = "https://api.parse.com/1/classes/english";
xmlhttp.open("POST", url, true);
xmlhttp.setRequestHeader("Content-type", "application/json");
xmlhttp.setRequestHeader("X-Parse-Application-Id", "VnxVYV8ndyp6hE7FlPxBdXdhxTCmxX1111111");
xmlhttp.setRequestHeader("X-Parse-REST-API-Key","6QzJ0FRSPIhXbEziFFPs7JvH1l11111111");
xmlhttp.onreadystatechange = function () { //Call a function when the state changes.
    if (xmlhttp.readyState == 4 && xmlhttp.status == 200) {
        alert(xmlhttp.responseText);
    }
}
var parameters = {
    "ephrase": "english",
    "pphrase": "farsi",
     "nvote": 0,
    "yvote": 0
};
// Neither was accepted when I set with parameters="username=myname"+"&password=mypass" as the server may not accept that

function doFunction() {
  xmlhttp.send(parameters);
}

</script>

xmlhttp.send(parameters);
             ^^^^^^^^^^

xmlhttp.setRequestHeader("Content-type", "application/json");

var xhr = new XMLHttpRequest();
            xhr.open("POST", "https://api.victorops.com/api-public/v1/incidents", true);
            xhr.setRequestHeader("X-VO-Api-Id", "your api_id");
            xhr.setRequestHeader("X-VO-Api-Key", "your api_key");
            xhr.setRequestHeader("Content-type", "application/json");
            xhr.setRequestHeader("Accept", "application/json");

            xhr.onreadystatechange = function () {

                if(xhr.readyState === XMLHttpRequest.DONE && xhr.status === 200) {
                    console.log(xhr.responseText);
                    console.log('yes');
                };
                if (xhr.status != 200) {
                    console.log( xhr.status + ': ' + xhr.statusText );
                    console.log('no');
                }
            };

            var json = JSON.stringify({
                summary: "data from your json",
                details: "data from your json",
                userName: "data from your json",
                targets: [
                    {
                        type: "data from your json",
                        slug: "data from your json"
                    }
                ]
            });
            xhr.send(json);