問題
第一問
var map = {x:1} //=> undefined
map //=> Object {x: 1}
map.toString //=> function toString() { [native code] }
map['toString'] = 1 //=> 1
map.toString //=> ?
delete map["toString"] //=> true
map.toString //=> ?
第二問
var map = {x:1} //=> undefined
map //=> Object {x: 1}
map.toString() //=> "[object Object]"
map['toString'] = 1
map.toString() //=> ?
delete map["toString"] //=> true
map.toString() //=> ?
答え
第一問
var map = {x:1} //=> undefined
map //=> Object {x: 1}
map.toString //=> function toString() { [native code] }
map['toString'] = 1 //=> 1
map.toString //=> 1
delete map["toString"] //=> true
map.toString //=> function toString() { [native code] }
第二問
var map = {x:1} //=> undefined
map //=> Object {x: 1}
map.toString() //=> "[object Object]"
map['toString'] = 1
map.toString() //=> Uncaught TypeError: map.toString is not a function
// at <anonymous>:1:5
delete map["toString"] //=> true
map.toString() //=> "[object Object]"