seperated_method_invocation.js

var methodInvoke = {
  des : "calling function owned by object",
  mean : function() {
    console.log(this===window);
    console.log('method invocation is a ' + this.des);
  }
}

var seperated_method = methodInvoke.mean
seperated_method() // >> true, 'method invocation is a undefined'