var foo = function(){
  var a=1
  console.log(a)
  a++
}
console.log('没有闭包')
foo()
foo()
foo()
foo()

var bar = (function(){
  var a=1
  var add=function(){
    a++
  }
  var log=function(){
    console.log(a)
  }
  return {add:add,log:log}
})()
console.log('有闭包')
bar.log()
bar.add()
bar.log()
bar.add()
bar.log()
bar.add()
bar.log()