Benchmark: JSON.parse() vs. eval() large object

Script Preparation code:

var jsonString = '{"user":{"id":1,"name":{"first":"太郎","last":"山田"},"age":30,"email":"taro.yamada@example.com","address":{"street":"1-2-3","city":"東京","prefecture":"東京都","postalCode":"100-0001"},"phoneNumbers":[{"type":"mobile","number":"090-1234-5678"},{"type":"home","number":"03-1234-5678"}],"hobbies":[{"name":"サッカー","level":"中級"},{"name":"読書","genres":["フィクション","ノンフィクション","ミステリー"]},{"name":"料理","skills":{"cuisine":["和食","イタリアン"],"level":"上級"}}],"preferences":{"language":"日本語","notifications":{"email":true,"sms":false,"push":true}}}}'

Tests:

JSON.parse()
var dummy = JSON.parse(jsonString);
eval()
eval('var dummy = ' + jsonString);

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
JSON.parse()
eval()

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: 8 months ago)

User agent: Mozilla/5.0 (X11; Linux x86_64; rv:143.0) Gecko/20100101 Firefox/143.0

Browser/OS: Firefox 143 on Linux

View result in a separate tab

Test name	Executions per second
JSON.parse()	256595.0 Ops/sec
eval()	32260.2 Ops/sec

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):

LLMs can make mistakes. Check important info.

The benchmark provided compares the performance of two methods for parsing a large JSON object in JavaScript: `JSON.parse()` and `eval()`. Here's a detailed explanation of the tests being conducted, the libraries and methodologies involved, as well as the performance characteristics of each approach.

### Benchmark Analysis

1. **Test Cases:**
   - **Benchmark #1: `JSON.parse()`**
     - This test case uses the native JavaScript function `JSON.parse()` to convert a string containing JSON data into a JavaScript object. 
     - **Pros:**
       - Safer: It does not execute any code within the JSON string thus reducing risks such as code injection vulnerabilities.
       - Standardized: It's part of the ECMAScript specification, meaning it is widely supported across different browsers.
       - Efficient: Optimized for parsing JSON, making it quicker to process large JSON strings.
     - **Cons:**
       - Limited to JSON data structures (e.g., no functions or undefined values can be directly parsed).

- **Benchmark #2: `eval()`**
     - This test case uses the `eval()` function, which takes a string and executes it as JavaScript code. The test string is prefixed with `'var dummy = '` to create a JavaScript variable on the fly.
     - **Pros:**
       - Flexible: Can parse any JavaScript code, including JSON that may involve functions and more complex types.
       - Capable of handling a wide range of JavaScript constructs.
     - **Cons:**
       - Security Risk: Using `eval()` can lead to security concerns, especially if the input is not trusted, as it may allow execution of arbitrary code.
       - Performance: Typically slower than `JSON.parse()` because it requires the JavaScript engine to evaluate the string as code rather than just parsing it as JSON.

### Performance Results
From the benchmark results:
- **`eval()` performed better**, executing **765,278.69 operations per second**.
- **`JSON.parse()` was slightly slower**, with **675,628.0 operations per second**.

### Other Considerations
- **Context of Use**: The choice between `JSON.parse()` and `eval()` often depends on the context of the application. For most scenarios involving JSON data, `JSON.parse()` is highly preferred due to its safety and performance.
- **Alternatives**: If performance is a critical concern and the JSON structure is known to be stable, alternatives like libraries that utilize faster parsing strategies (e.g., `json2.js` or `fast-json-parse`) can be employed to further enhance JSON parsing speed.
- **Real-World Application**: In real-world applications, security should always be the primary consideration when parsing data. For handling JSON data obtained from external sources, `JSON.parse()` is favored, while `eval()` should be avoided unless absolutely necessary and safe.

### Summary
In summary, the benchmark provides a clear comparison between the two methods of parsing JSON data in JavaScript. Most use cases will benefit from the safer and faster `JSON.parse()`, while `eval()` can be considered when flexibility is needed but should come with caution due to associated security risks. Understanding these trade-offs helps software engineers make informed decisions based on the specific requirements and contexts of their applications.

Related benchmarks:

JSON.parse() vs. eval() large object (version: 1)

Comparing performance of: JSON.parse() vs eval()

Created: one year ago by: Guest

Jump to the latest result

JSON.parse()

eval()

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model gpt-4o-mini, generated one year ago):