Is Convert Object to JSON String easy or hard?

The problem is rated Medium because it requires careful handling of multiple data types and nested structures. The recursion itself is straightforward, but correctly formatting arrays, objects, and strings without using built-in serializers adds complexity.

Convert Object to JSON String Python/Java solution

The same idea applies across languages. Implement a recursive function that checks the value type, serializes primitives, iterates arrays, and processes object/dictionary entries. Each language builds the final string using concatenation or join operations.

How to solve Convert Object to JSON String in O(n)?

Use a recursive function that serializes values based on their type. Convert primitives directly, iterate through arrays and recursively serialize elements, and iterate through object keys to serialize key-value pairs. Because each node in the structure is visited once, the overall complexity remains O(n).

What is the best approach for Convert Object to JSON String?

The best approach is recursive traversal of the object structure. Check the type of each value, directly serialize primitives, and recursively process arrays and nested objects. Every element is visited once, producing an O(n) time solution with O(n) space for the output string and recursion stack.

Is Convert Object to JSON String asked at Google/Amazon/Meta?

Serialization and nested data traversal problems frequently appear in interviews at large tech companies. Variants of custom JSON serialization test recursion, type handling, and string construction skills often evaluated in frontend and full‑stack interviews.

What data structure is used in Convert Object to JSON String?

The solution operates on nested JavaScript objects and arrays. Recursion is used to traverse the structure, and strings are incrementally constructed to build the final JSON representation.

What is the time complexity of Convert Object to JSON String?

The time complexity is O(n), where n is the total number of values and properties in the object structure. Each element, array entry, or object key-value pair is processed exactly once during the recursive traversal.

Description Hints 3 Solution Video 12:26

2633. Convert Object to JSON String

Medium77.4% acceptance2 companiesPremium elsewhere, free here

Given a value, return a valid JSON string of that value. The value can be a string, number, array, object, boolean, or null. The returned string should not include extra spaces. The order of keys should be the same as the order returned by Object.keys().

Please solve it without using the built-in JSON.stringify method.

Example 1:

Input: object = {"y":1,"x":2}
Output: {"y":1,"x":2}
Explanation: 
Return the JSON representation.
Note that the order of keys should be the same as the order returned by Object.keys().

Example 2:

Input: object = {"a":"str","b":-12,"c":true,"d":null}
Output: {"a":"str","b":-12,"c":true,"d":null}
Explanation:
The primitives of JSON are strings, numbers, booleans, and null.

Example 3:

Input: object = {"key":{"a":1,"b":[{},null,"Hello"]}}
Output: {"key":{"a":1,"b":[{},null,"Hello"]}}
Explanation:
Objects and arrays can include other objects and arrays.

Example 4:

Input: object = true
Output: true
Explanation:
Primitive types are valid inputs.

Constraints:

value is a valid JSON value
1 <= JSON.stringify(object).length <= 10⁵
maxNestingLevel <= 1000
all strings contain only alphanumeric characters

Asked at 2 companies

Apple

Google

Hints open one at a time

Hint 1

Consider the 4 possibilities. The object could be an array, an object, a string, or another type.

Hint 2

Think about the problem recursively. If you know how to convert any sub-data into a string, how could you use it to convert the entire data into a string?

Hint 3

If the data is a string, it's just the value surrounded by double quotes. If the data is another type, its just String(data). If the data is an array, it's the recursively stringified value of each item separated by commas. If the data is an object, it's a series of key-value pairs where each value is the recursively stringified value.

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2633. Convert Object to JSON String

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