小编Kev*_*kin的帖子

var a = {}
var b = {}

try{
  a.x.y = b.e = 1 // Uncaught TypeError: Cannot set property 'y' of undefined
} catch(err) {
  console.error(err);
}
console.log(b.e) // 1

var a = {}
var b = {}

try {
  a.x.y.z = b.e = 1 // Uncaught TypeError: Cannot read property 'y' of undefined
} catch(err) {
  console.error(err);
}

console.log(b.e) // undefined