👀 Views: 0 💬 Answers: 1 📅 Created: 2025-06-19

json parsing javascript JavaScript

I'm working on a project and hit a roadblock. I'm relatively new to this, so bear with me. I'm trying to parse a deeply nested JSON structure in JavaScript, where some keys are dynamic and aren't known until runtime. For instance, I have a response from an API that looks like this: ```json { "user": { "name": "John", "age": 30, "preferences": { "theme": "dark", "languages": ["JavaScript", "Python"] } }, "metadata": { "date": "2023-10-01", "dynamicKey": { "subKey1": "value1", "subKey2": "value2" } } } ``` I want to access the values of `subKey1` and `subKey2` under `dynamicKey`, but I'm unsure how to navigate through the structure when the key `dynamicKey` might change based on the API response. I've tried this code: ```javascript const response = /* JSON response from API */; const dynamicKey = "dynamicKey"; // This will change based on runtime conditions const subKey1Value = response.metadata[dynamicKey].subKey1; const subKey2Value = response.metadata[dynamicKey].subKey2; ``` However, when `dynamicKey` doesn't exist in the response, I get an behavior: `TypeError: want to read properties of undefined (reading 'subKey1')`. I attempted using optional chaining like this: ```javascript const subKey1Value = response.metadata[dynamicKey]?.subKey1; const subKey2Value = response.metadata[dynamicKey]?.subKey2; ``` While this prevents the behavior, it returns `undefined`, which I assume means that `dynamicKey` is not being matched correctly. I've also tried checking if the key exists before accessing it, but I'm struggling with the logic. What’s the best way to handle this scenario effectively? I’m using Node.js v16.14.0 with no additional libraries for parsing the JSON. I appreciate any insights!