【前端】iterable类型的 forEach方法

a = [
    age: 1
  ,
    age: 2
]

a.forEach (item) ->
  item.age = 0 # 有效
  
console.log a 
# [
#     age: 0
#   , 
#     age: 0
# ]

b = [1, 2]

b.forEach (item) ->
  item = 0 # 无效 

console.log b
# [1, 2]

b = [1, 2]

b.forEach (item, index, arr) ->
  arr[index] = 0 # 有效

console.log b
# [1, 2]