This is working in node 0.7.7

output

$ node unicode.js
buf= <Buffer 5b 22 f0 9f 92 a9 22 0a 2c 22 f0 9f 98 81 22 0a 2c 22 5c 75 64 38 33 64 5c 75 64 63 61 39 22 0a 2c 22 5c 75 64 38 33 64 5c 75 64 65 30 31 22 0a 5d 0a>
str= ["💩"
,"😁"
,"\ud83d\udca9"
,"\ud83d\ude01"
]

obj= [ '💩', '😁', '💩', '😁' ]
obj[0]= 💩
obj[0].length= 2
obj[0].charAt(0)= ?
obj[0].charCodeAt(0)= d83d
obj[0].charAt(1)= ?
obj[0].charCodeAt(1)= dca9
obj[1]= 😁
obj[1].length= 2
obj[1].charAt(0)= ?
obj[1].charCodeAt(0)= d83d
obj[1].charAt(1)= ?
obj[1].charCodeAt(1)= de01
obj[2]= 💩
obj[2].length= 2
obj[2].charAt(0)= ?
obj[2].charCodeAt(0)= d83d
obj[2].charAt(1)= ?
obj[2].charCodeAt(1)= dca9
obj[3]= 😁
obj[3].length= 2
obj[3].charAt(0)= ?
obj[3].charCodeAt(0)= d83d
obj[3].charAt(1)= ?
obj[3].charCodeAt(1)= de01

unicode.js

var fs = require("fs")
var buf = fs.readFileSync("unicode.json")
console.error("buf=", buf)
var str = buf.toString("utf8")
console.error("str=", str)
var obj = JSON.parse(str)
console.error("obj=", obj)

obj.forEach(function (char, pos) {
  console.error("obj[%d]=", pos, obj[pos])
  console.error("obj[%d].length=", pos, obj[pos].length)
  for (var i = 0; i < obj[pos].length; i ++) {
    console.error("obj[%d].charAt(%d)=", pos, i, obj[pos].charAt(i))
    console.error("obj[%d].charCodeAt(%d)=", pos, i, obj[pos].charCodeAt(i).toString(16))
  }
})

unicode.json

["💩"
,"😁"
,"\ud83d\udca9"
,"\ud83d\ude01"
]