Benchmark: Spread it and Assign Again

Script Preparation code:

var data = {
  'one': [{
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    }
], 'two': [{
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
          replace: "yes",
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    },
    {
        foo: {
            bar: {
                baz: "hi"
            }
        }
    }
]
};

Tests:

map
let f = { ...data, two: data.two.map((item) => { item.foo.replace == "yes" ? { ...item, something: { n: 234, b: 234 } } : item }), };
empty assign
let o = Object.assign({}, data, { two: data.two.map((item) => { item.foo.replace == "yes" ? { ...item, something: { n: 234, b: 234 } } : item }) })
data assign
let o = Object.assign(data, { two: data.two.map((item) => item.foo.replace == "yes" ? { ...item, something: { n: 234, b: 234 } } : item ) });
in place mod
let f = data.two.find((item) => item.foo.replace == "yes"); f.n = 234; f.b = 234; data

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
map
empty assign
data assign
in place mod

Fastest: N/A

Slowest: N/A

Latest run results:

No previous run results

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

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I'll break down the benchmark and explain what's being tested, the options compared, their pros and cons, and other considerations.

**Benchmark Overview**

The test case "Spread it and Assign Again" uses an object `data` with nested properties to demonstrate the performance of different JavaScript methods for modifying objects. The main objective is to compare the execution speed of various approaches that achieve the same result.

**Benchmark Definition JSON**

The benchmark definition includes:

*   A script preparation code: This defines the `data` object, which contains multiple levels of nesting.
*   Individual test cases:
    *   "map" (4 iterations)
    *   "empty assign" (1 iteration)
    *   "data assign" (1 iteration)
    *   "in place mod" (1 iteration)

**Test Cases**

Each test case uses a different method to modify the `data` object:

*   **"map"`: Uses the `Array.prototype.map()` method to create a new array with modified objects.
*   **"empty assign"`: Uses `Object.assign({}, data, { ... })` to merge two objects and create a new one.
*   **"data assign"`: Uses `Object.assign(data, { ... })` to merge two objects into the existing `data` object.
*   **"in place mod"`: Directly modifies individual objects within the nested structure.

**Options Compared**

The benchmark compares the execution speed of four different methods:

1.  **`map()`**: Creates a new array with modified objects, which can be slower due to the overhead of creating a new array and iterating over each element.
2.  **"empty assign"`: Merges two objects using `Object.assign`, which creates a new object and copies properties from one object into another.
3.  **"data assign"`: Merges two objects into an existing object, also using `Object.assign`. This approach modifies the original data in-place.
4.  **"in place mod"`: Directly modifies individual objects within the nested structure.

**Pros and Cons**

*   **`map()`**: Pros:
    *   More concise code
    *   Encapsulates modification logic within a single function call
Cons:
    *   Creates a new array, which can be slower due to memory allocation and garbage collection.
*   **"empty assign"`: Pros:
    *   Easy to understand and implement
Cons:
    *   Creates a new object, which incurs additional overhead.
*   **"data assign"`: Pros:
    *   Modifies the original data in-place
Cons:
    *   Can be less readable due to nested `Object.assign()` calls
*   **"in place mod"`: Pros:
    *   Fastest execution time (directly modifying objects)
Cons:
    *   Requires manual manipulation of object properties

**Other Considerations**

*   The benchmark uses a fixed set of test cases and inputs, which may not reflect real-world usage scenarios.
*   Different browsers or JavaScript engines might have varying performance characteristics for each method.

Overall, this benchmark helps identify the most efficient approach for modifying objects in JavaScript, considering factors such as execution speed, memory allocation, and code readability.

Related benchmarks:

Spread it and Assign Again (version: 0)

Comparing performance of: map vs empty assign vs data assign vs in place mod

Created: 3 years ago by: Guest

Jump to the latest result

map

empty assign

data assign

in place mod

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):