一、

var name = "The Window";

var object = {
  name : "My Object",

  getNameFunc : function(){
    return function(){
      return this.name;
    };
  }
};

console.log(object.getNameFunc()()); // 'The window'

二、

var name = "The Window";

var object = {
  name : "My Object",

  getNameFunc : function(){
    var that = this;
    return function(){
      return that.name;
    };
  }
};

console.log(object.getNameFunc()());  // 'My Object'

三、

var fnArr = [];
for (var i = 0; i < 10; i ++) {
  fnArr[i] =  function(){
    return i
  };
}
console.log( fnArr[3]() ) // 输出10

改造后，输出3

第一种方法：
var fnArr = []
for (var i = 0; i < 10; i ++) {
  fnArr[i] =  (function(j){
    return function(){
      return j
    } 
  })(i)
}
console.log( fnArr[3]() ) // 3

第二种方法：
var fnArr = []
for (var i = 0; i < 10; i ++) {
  (function(i){
    fnArr[i] =  function(){
      return i
    } 
  })(i)
}
console.log( fnArr[3]() ) // 3

第三种方法：let是声明一个块级作用域的本地变量
var fnArr = []
for (let i = 0; i < 10; i ++) {
  fnArr[i] =  function(){
    return i
  } 
}
console.log( fnArr[3]() ) // 3

四、封装一个Car对象

var Car = (function(){
  var speed = 0;
  function set(s){
      speed = s
  };
  function get(){
      return speed
  };
  function speedUp(){
      speed++
  };
  function speedDown(){
      speed--
  };
  return {
      set: set,
      get: get,
      speedUp: speedUp,
      speedDown: speedDown
  };
})()
Car.set(30)
Car.get() //30
Car.speedUp()
Car.get() //31
Car.speedDown()
Car.get()  //30

五、

for(var i=0; i<5; i++){
  setTimeout(function(){
    console.log('delayer:' + i )
  }, 0)
}
//输出五次 5

改造后，连续输出 0,1,2,3,4

for(var i=0; i<5; i++){
  (function(j){
    setTimeout(function(){
      console.log('delayer:' + j )
    }, 0)    
  })(i)
}

或者
for(var i=0; i<5; i++){
  setTimeout((function(j){
    return function(){
      console.log('delayer:' + j )
    }
  }(i)), 0)    
}

六、

function makeCounter() {
  var count = 0
  return function() {
    return count++
  };
}

var counter = makeCounter();
var counter2 = makeCounter();

console.log( counter() ) // 0
console.log( counter() ) // 1

console.log( counter2() ) // 0
console.log( counter2() ) // 1

七、数组按姓名、年纪、任意字段排序

var users = [
  { name: "John", age: 20, company: "Baidu" },
  { name: "Pete", age: 18, company: "Alibaba" },
  { name: "Ann", age: 19, company: "Tecent" }
]

function byField(field){
  return function(user1, user2){
    return user1[field] > user2[field]
  }
}

users.sort(byField('name'))
users.sort(byField('age'))
users.sort(byField('company'))

八、 sum 函数

function sum(a) {
  return function(b) {
    return a + b
  }
}

console.log( sum(1)(2) ) // 3
console.log( sum(5)(-1) ) // 4

九、实现 console.log(sum(1)(2)...(98)(99)) // 5050

function sum(a) {
  function s(b) {
    a += b
    return s
  }
  s.toString = function(){return a}
  return s
}