你想復(fù)制一個(gè)對(duì)象,包含其所有子對(duì)象。
clone = (obj) ->
if not obj? or typeof obj isnt 'object'
return obj
if obj instanceof Date
return new Date(obj.getTime())
if obj instanceof RegExp
flags = ''
flags += 'g' if obj.global?
flags += 'i' if obj.ignoreCase?
flags += 'm' if obj.multiline?
flags += 'y' if obj.sticky?
return new RegExp(obj.source, flags)
newInstance = new obj.constructor()
for key of obj
newInstance[key] = clone obj[key]
return newInstance
x =
foo: 'bar'
bar: 'foo'
y = clone(x)
y.foo = 'test'
console.log x.foo isnt y.foo, x.foo, y.foo
# => true, bar, test
通過(guò)賦值來(lái)復(fù)制對(duì)象與通過(guò)克隆函數(shù)來(lái)復(fù)制對(duì)象的區(qū)別在于如何處理引用。賦值只會(huì)復(fù)制對(duì)象的引用,而克隆函數(shù)則會(huì):
下面是一個(gè)通過(guò)賦值來(lái)復(fù)制對(duì)象的例子:
x =
foo: 'bar'
bar: 'foo'
y = x
y.foo = 'test'
console.log x.foo isnt y.foo, x.foo, y.foo
# => false, test, test
顯然,復(fù)制之后修改 y 也就修改了 x。