Tesla (1+ Interviews) | Interview Experiences

Summary

I just completed an online screening with Tesla where I was presented with a detailed problem requiring the implementation of a JSONPath Evaluator, which felt like a variation on the Basic Calculator problems.

Full Experience

I underwent an online screening with Tesla. The core of the interview revolved around solving a complex programming challenge. The problem presented was titled 'JSONPath Evaluator' and required me to implement a function capable of parsing and evaluating JSONPath expressions against a given JSON object, similar in complexity to advanced calculator problems.

Interview Questions (1)

JSONPath Evaluator

Data Structures & AlgorithmsHard

Problem Description

Implement a function that evaluates JSONPath expressions to extract data from a JSON object. JSONPath is a query language for JSON, similar to how XPath is used for XML.

Your task is to implement the evalJq(json_data, expression) function that takes a JSON object and a JSONPath expression and returns the corresponding value(s) from the JSON data.

JSONPath Expression Syntax

Your implementation should support the following JSONPath features:

$ - The root object/element
.property - Child operator (access direct properties)
[index] - Array index expressions to access array elements
[start:end] - Array slice operator to get a range of elements

Examples

For the following JSON data:

{
  "traveler": "Alex Johnson",
  "passport": "AB123456",
  "mileagePoints": 75000,
  "homeAirport": {
    "code": "SFO",
    "name": "San Francisco International",
    "country": "USA"
  },
  "recentFlights": [
    {
      "flightNumber": "UA456",
      "from": "SFO",
      "to": "JFK",
      "date": "2025-03-15",
      "class": "business"
    },
    {
      "flightNumber": "LH789",
      "from": "JFK",
      "to": "FRA",
      "date": "2025-03-20",
      "class": "economy"
    },
    {
      "flightNumber": "BA321",
      "from": "FRA",
      "to": "LHR",
      "date": "2025-03-22",
      "class": "premium"
    }
  ]
}

The function should return:

- `evalJq(data, "$")` → The entire JSON object
- `evalJq(data, "$.traveler")` → "Alex Johnson"
- `evalJq(data, "$.homeAirport.code")` → "SFO"
- `evalJq(data, "$.mileagePoints")` → 75000
- `evalJq(data, "$.recentFlights[0].flightNumber")` → "UA456"
- `evalJq(data, "$.recentFlights[2].class")` → "premium"
- `evalJq(data, "$.recentFlights[:].to")` → ["JFK", "FRA", "LHR"]

Constraints

The input JSON data will be a valid JSON object.
The JSONPath expression will be a valid string following the syntax described above.
You must handle nested objects and arrays.
For array slice notation [start:end], if either start or end is missing, it should be treated as the start or end of the array respectively.

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