03 JSON.parse.js

// evel
function jsonParse(opt) {
  return eval("(" + opt + ")");
}

// 校验参数，避免 XSS 攻击
function jsonParse2(json) {
  var rx_one = /^[\],:{}\s]*$/;
  var rx_two = /\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g;
  var rx_three = /"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g;
  var rx_four = /(?:^|:|,)(?:\s*\[)+/g;
  if (
    rx_one.test(
      json
        .replace(rx_two, "@")
        .replace(rx_three, "]")
        .replace(rx_four, "")
    )
  ) {
    var obj = eval("(" + json + ")");
    return obj;
  }
}

// Function
var jsonStr = '{ "age": 20, "name": "jack" }';
var json = new Function("return " + jsonStr)();

console.log(jsonParse2(JSON.stringify({ x: 5 })));
console.log(jsonParse2(JSON.stringify([1, "false", false])));
console.log(jsonParse2(JSON.stringify({ b: undefined })));