Cast a String Array of JSON Objects to JSON in Javascript

I recently encountered a scenario where I needed to store an array of objects locally for later retrieval. The challenge was converting this array of objects into a string before saving it and then cast a string array of JSON objects to JSON. This led me to figure out how to cast a string array of JSON objects back to JSON in JavaScript. For those seeking a quick solution, here’s the approach:

The Solution to Cast a String Array of JSON Objects to JSON in Javascript

// Create the string representation of the array
let data = '[{"data_one":"a", "data_two":"b"}]';

// Parse the string back into a JSON object
let jsonData = JSON.parse(data);

// Access elements as usual
console.log(jsonData[0]); // Outputs: { data_one: 'a', data_two: 'b' }

If you’re interested in understanding the problem in more detail, let’s dive deeper.

The Setup

• Environment: Node v12.10.0
• Platform: macOS

Recreating the Parsing Issue

Initially, when attempting to access the first element of the array, I encountered unexpected behavior:

// Create the string representation of the array
let data = '[{"data_one":"a", "data_two":"b"}]';

// Attempt to access the first character
console.log(data[0]); // Outputs: '['

This output occurs because data is a string, so accessing data[0] returns the first character of the string, which is '['. To work with the data as an array of objects, it’s essential to parse the string into a JSON object:

// Parse the string into a JSON object
let jsonData = JSON.parse(data);

// Access the first object in the array
console.log(jsonData[0]); // Outputs: { data_one: 'a', data_two: 'b' }

// Access a specific property
console.log(jsonData[0]["data_one"]); // Outputs: 'a'

By using JSON.parse(), the string is converted back into a JSON object, allowing for standard array operations.

Additional Insights

This situation is reminiscent of a similar issue I encountered in Python, where I learned that list indices must be integers. Understanding how different programming languages handle data types and structures is crucial for effective debugging and development.

For more information on parsing JSON in JavaScript, you might find this resource helpful:

• JSON.parse() – W3Schools

Happy coding! Check out this article on how to filter an array of objects in JS for more practice.