function createNewOpportunityFromCase() {
var xhttp = new XMLHttpRequest();
xhttp.open("POST", "services/apexrest/CaseToProject", true);
xhttp.setRequestHeader("Authorization", "Bearer {!$Api.Session_ID}");
xhttp.setRequestHeader("Content-Type", "application/json");
var payload = {"caseId" : "{!Case.Id}"};
xhttp.send(payload);
}
createNewOpportunityFromCase();