this is tricky

this-is-tricky----illustration.js

var hello= 'bonjour';

var will = {
 hello : 'hello',
 tab : [1,2],
 say : function(){
    console.info(this.hello)
  },
 iterateSay : function(){
     this.tab.every(function(value, index){ 
       console.info(this.hello);
       return false;
     })
     //solution to keep this context : bind to expected this
     //this.tab.every(function(value, index){ 
     //  console.info(this.hello);
     //  return false;
     //}.bind(this))     
  }
}

//borrowed function
var test = will.say; 
console.info(will.say()); //say : 'hello' - will context as expected
console.info(test());     //this when in a borrowed function won't execute in same context
//solution : 
//console.info(test.call(will));



//closure
will.say();    //say : 'hello' - will context as expected
will.iterateSay(); //this when in a closure function execute in global context