Benchmark: Reading object values in loop: Object.keys vs Object.values

Script Preparation code:

var obj = {};

for (let i = 0; i < 1000; i++) {
  obj['abc_' + i] = i;
}

Tests:

Object.keys
const keys = Object.keys(obj); keys.forEach(function(key, value) { console.log(obj[key]); });
Object.values
const values = Object.values(obj); values.forEach(function(key, value) { console.log(value); });

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
Object.keys
Object.values

Fastest: N/A

Slowest: N/A

Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36

Browser/OS: Chrome 133 on Windows

View result in a separate tab

Test name	Executions per second
Object.keys	478.2 Ops/sec
Object.values	481.3 Ops/sec

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):

LLMs can make mistakes. Check important info.

**Overview of the Benchmark**

The provided benchmark measures the performance difference between two approaches to access values in an object: `Object.keys` and `Object.values`. The test creates an object with 1000 properties, each initialized with a unique value.

**Options Compared**

Two options are compared:

1. **Object.keys**: Returns an array of strings representing the keys of the object.
2. **Object.values**: Returns an array of values of the object.

**Pros and Cons of Each Approach**

*   **Object.keys**:
    *   Pros: More explicit control over accessing object properties, can be used for iteration with custom key-value pairs.
    *   Cons: Requires additional indexing to access values (`obj[key]`), which can lead to slower performance due to string lookup.
*   **Object.values**:
    *   Pros: Faster access to values since it avoids string lookup and directly returns the values as an array. However, it only provides direct access to object values without iteration capabilities.
    *   Cons: Less flexible for custom iteration logic.

**Library Used (None)**

No specific library is used in this benchmark. The test relies solely on built-in JavaScript features.

**Special JS Feature/Syntax**

There are no special JavaScript features or syntaxes explicitly mentioned or utilized in the provided code.

**Other Alternatives**

If you needed to access object properties, some other alternatives could be considered:

*   Using a `for...in` loop directly on the object (similar to using `Object.keys` but potentially slower due to string lookup): `for (var key in obj) { console.log(obj[key]); }`
*   Utilizing modern JavaScript features like `Object.entries()` or `Array.from()`: `Object.entries(obj).forEach(([key, value]) => { console.log(value); });`

However, for simple access cases with direct values, using `Object.values` is still the recommended approach due to its performance benefits.

**Benchmark Preparation Code Analysis**

The provided preparation code creates an object (`obj`) and populates it with 1000 properties. The script then uses a loop to iterate over these properties, assigning each property a unique value between 0 and 999.

**Individual Test Cases Analysis**

Two test cases are defined:

*   **Object.keys**: Uses `Object.keys()` to get an array of keys from the object and then iterates through this array using a `forEach` callback function to log the corresponding values.
*   **Object.values**: Directly uses `Object.values()` to get an array of values from the object, iterating over it with another `forEach` callback function to log each value.

These test cases are intended to compare the performance and behavior of these two approaches in a simple scenario.

Related benchmarks:

Reading object values in loop: Object.keys vs Object.values (version: 1)

Comparing performance of: Object.keys vs Object.values

Created: 7 years ago by: Registered User

Jump to the latest result

Object.keys

Object.values

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

Autogenerated LLM Summary (model llama3.2:3b, generated one year ago):