get the groups of current user using REST API

  I need to the group of the current user : this is my code

function checkGroup() {

var group = [“Directeur des ventes”, “Superviseur”, “VM”, “CP”];
for (var i = 0; i < group.length; i++) {
if (isMember(group[i]) == true)
{

alert(‘je suis membre du group’+ i);
break;
}
}

}

function isMember(groupName){
$.ajax({
url: _spPageContextInfo.webAbsoluteUrl + “/_api/web/sitegroups/getByName(‘”+groupName+”‘)/Users?$filter=Id eq ‘” + _spPageContextInfo.userId+”‘”,
method: “GET”,
headers: { “Accept”: “application/json; odata=verbose”},
success: function (data) {
alert(‘im member of group’ + groupName);
return true;

},
async: false,
});
}

but il always get alert('im member of group' + groupName); !!


any idea ,