[クイズ]javascriptと仲良くなるための一歩 第４２話「this参照１」

問題

var obj = {
           x:3,
           doit: function(){ console.log("method is called." + this.x); }
          }
obj.doit(); //=> method is called.3

var fn = obj.doit;
var x = 5;
fn(); //=> ?

答え

var obj = {
           x:3,
           doit: function(){ console.log("method is called." + this.x); }
          }
obj.doit(); //=> method is called.3

var fn = obj.doit;
var x = 5;
fn(); //=> method is called.5