在javascript中评估类似路径的表达式的简单方法?

JSONPath

var x = {foo: 42, bar: {fubar: true}}
var res1 = jsonPath(x, "$.bar.fubar"); // Array containing fubar's value

function evalPath(obj, path)
{
    var rtnValue = obj;

    // Split our path into an array we can iterate over
    var path = path.split(".");
    for (var i = 0, max=path.length; i < max; i++) 
    {
        // If setting current path to return value fails, set to null and break
        if (typeof (rtnValue = rtnValue[path[i]]) == "undefined")
        {
            rtnValue = null;
            break;
        }
    }

    // Return the final path value, or null if it failed
    return rtnValue;
}

eval

function locate(obj, path) {
    var p = path.split("."), a = p.shift();
    if(a in obj)
       return p.length ? locate(obj[a], p.join(".")) : obj[a];
     return undefined;
}

locate(x, "bar.fubar")

function evalPath(obj, path) {
  var pathLevels = path.split('.');
  var result = obj;
  for (var i = 0; i < pathLevels.length; i++) {
    try {
      result = result[pathLevels[i]];
    }
    catch (e) {
      alert('Property not found:' + pathLevels[i]);
    }
  }
  return result;
}

alert null

evalPath = function(obj, path) {
  if (path[0] === "[") {
    return eval("obj" + path);
  } else {
    return eval("obj." + path);
  }
};