How I can skip the element of array .map?

This is what Array.prototype.filter() is for. You need to do this in two steps.

var userids = userbody.contacts
    .filter(contact => contact.iAccepted == 'true' && contact.contactAccepted == 'true')
    .map(contact => contact.userId);

The filter part takes out all unnecessary elements, then map converts the rest to the way you want.

you can use flatMap

The flatMap() method returns a new array formed by applying a given callback function to each element of the array, and then flattening the result by one level. It is identical to a map() followed by a flat() of depth 1, but slightly more efficient than calling those two methods separately.

var userids = userbody.contacts.flatMap((obj)=>{
  if((obj.iAccepted=='true')&&(obj.contactAccepted=='true')) {
    return obj.userID 
  } 
  else{
    return[];
  }

});

You can use Array.reduce function to implement Array.map and Array.filter process in one function as follows.

const userIds = userbody.contacts.filter((acc, cur) => {
  if((obj.iAccepted == 'true') && (obj.contactAccepted == 'true')) {
    acc.push(obj.userID);
  }
  return acc;
}, []);
console.log(userIds);