下面这个例子（http://sina.lt/fQNW）来理解let或const关键字声明的变量如何工作。
let movie ="Lord of the Rings";
//var movie = "Batman v Superman";
function starWarsFan(){
const movie = 'Star Wars';
return movie;
}
function marvelFan(){
movie = "The Avengers";
return movie;
}
function blizzardFan(){
const isFan = true ;
let phrase = 'Warcraft';
console.log('Before if:'+ phrase);
if(isFan){
let phrase = 'initial text';
phrase = 'For the Horde!';
console.log('After if:'+ phrase);
}
phrase = 'For the Alliance!';
console.log('After if:' + phrase);
}
console.log(movie);//Lord of Rings
console.log(starWarsFan());//Star Wars
console.log(marvelFan());//The Avengers
console.log(movie);//The Avengers
blizzardFan();//Before if: Warcraft Inside if : For the Horde! After if : For the Alliance!
