var params = { b:"hello", c: true, d:7 };
var other = Object.assign({ a: 2 }, params);
var params = { b:"hello", c: true, d:7 };
var other = { a: 2, params };
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
Object.assign | |
spread operator |
Test name | Executions per second |
---|---|
Object.assign | 2995577.8 Ops/sec |
spread operator | 10320246.0 Ops/sec |
Let's break down the provided benchmark and explain what's being tested, compared, and considered.
Benchmark Overview
The benchmark compares two approaches for creating a new object: Object.assign
and the spread operator ({ ...params }
). The test is designed to measure the performance difference between these two methods on a fixed input dataset.
Approaches Compared
There are two approaches being compared:
Object.assign
: This method takes multiple arguments and merges them into a new object. In this benchmark, Object.assign
is used to merge an existing object ({ a: 2 }
) with a new set of properties (params
).{ ...params }
): This syntax creates a new object by copying the properties from params
and merging them into the existing object ({ a: 2 }
).Pros and Cons
Object.assign
:
Pros:
Cons:
Spread Operator ({ ...params }
):
Pros:
Object.assign
Cons:
Library Usage
In this benchmark, no libraries are used. The test only involves native JavaScript features.
Special JS Features/Syntax
The spread operator ({ ...params }
) is a modern JavaScript feature that's introduced in ECMAScript 2018 (ES8). It allows for concise object creation by copying properties from an existing object or array.
Other Considerations
When choosing between Object.assign
and the spread operator, consider the following:
Object.assign
may be preferred due to its explicit nature.Alternative Approaches
Other approaches for creating a new object could include:
Object.create()
methodconst obj = { ... }
)