Benchmark: "delete" vs "spread syntax" vs "set to undefined"

Script Preparation code:

var obj = {
  a: 1,
  b: 2,
  c: 3,
  d: 4,
  e: 5,
  f: 6,
  g: 7,
  h: 8,
  i: 9,
  j: 10,
  k: 11,
  l: 12,
  m: 13,
  n: 14,
  o: 15,
  p: 16,
  q: 17,
  r: 18,
  s: 19,
  t: 20,
  u: 21,
  v: 22,
  w: 23,
  x: 24,
  y: 25,
  z: 26
};

Tests:

delete
delete obj['c'] delete obj['f'] delete obj['i'] delete obj['l'] delete obj['o'] delete obj['r'] delete obj['u'] delete obj['x']
set to undefined
obj['c'] = undefined obj['f'] = undefined obj['i'] = undefined obj['l'] = undefined obj['o'] = undefined obj['r'] = undefined obj['u'] = undefined obj['x'] = undefined
spread syntax
const {c, ...restC} = obj const {f, ...restF} = obj const {i, ...restI} = obj const {l, ...restL} = obj const {o, ...restO} = obj const {r, ...restR} = obj const {u, ...restU} = obj const {x, ...restX} = obj

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
delete
set to undefined
spread syntax

Fastest: N/A

Slowest: N/A

Latest run results:

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

LLMs can make mistakes. Check important info.

Measuring the performance of different JavaScript approaches can be a fascinating and complex task. Let's break down what's being tested in this benchmark.

**What is being tested?**

The benchmark compares three different ways to delete properties from an object:

1. **"delete"**: The traditional `delete` keyword is used to delete properties.
2. **"set to undefined"**: The property value is set to `undefined`.
3. **"spread syntax"**: An object literal is created with the desired properties, and then the `...` spread operator is used to create a new object that excludes the unwanted properties.

**What options are being compared?**

The three approaches offer different trade-offs:

* **Performance**: Deleting properties using the `delete` keyword is likely to be faster than setting property values to `undefined`, which might incur additional overhead due to memory management. The spread syntax approach, however, may be slower since it involves creating a new object and assigning it to a variable.
* **Memory usage**: Setting property values to `undefined` does not free up the original memory allocation, whereas deleting properties using the `delete` keyword or the spread syntax might have different implications for memory management.
* **Code readability and maintainability**: The spread syntax approach can make the code more explicit and easier to understand, while the `delete` keyword can be less readable in some cases. Setting property values to `undefined` can also lead to unclear intent if not done carefully.

**Library usage**

In this benchmark, the `const` and `let` keywords are used with destructuring assignment (e.g., `const {c, ...restC} = obj`). The `const` keyword is used to create constant variables that cannot be reassigned. In JavaScript, `const` and `let` provide different scoping behaviors, which can affect performance.

**Special JS features or syntax**

This benchmark does not use any special JavaScript features or syntax, such as async/await, Promises, or async functions, which might offer alternative approaches for deleting properties.

**Other alternatives**

If you need to delete properties from an object in a different context, consider the following alternatives:

* **Using `Object.prototype.hasOwnProperty.call()`**: This method is often used when iterating over property names and checking if they exist.
* **Using `for...in` loop with an empty object**: This approach involves creating an empty object and using the `for...in` loop to iterate over the original object's properties, which can be useful for deleting properties while preserving their order.
* **Using a library or function specifically designed for property deletion**: Depending on your specific use case, you might find libraries like Lodash's `omit()` or `pick()` functions useful.

In summary, this benchmark provides a simple and straightforward way to compare the performance of different approaches to delete properties from an object. Understanding the trade-offs between these approaches can help you choose the best solution for your specific use case.

Related benchmarks:

"delete" vs "spread syntax" vs "set to undefined" (version: 0)

Comparing performance of: delete vs set to undefined vs spread syntax

Created: 2 years ago by: Guest

Jump to the latest result

delete

set to undefined

spread syntax

Suite status: <idle, ready to run>

Fastest: N/A

Slowest: N/A

No previous run results

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