var array = [1,2,3,4,5,6,7,8,9];var array2 = [1,1,1];array.unshift(array2);array = array.concat(array2)array = [array2 , array]--enable-precise-memory-info flag.
| Test case name | Result |
|---|---|
| arrayUnshift123 | |
| arrayConcat123 | |
| arraySpread123 |
| Test name | Executions per second |
|---|---|
| arrayUnshift123 | 19592.8 Ops/sec |
| arrayConcat123 | 376.4 Ops/sec |
| arraySpread123 | 89.7 Ops/sec |
Let's dive into the world of JavaScript microbenchmarks on MeasureThat.net.
What is being tested?
The provided JSON represents a benchmark test case that compares three different approaches to add elements to an array in JavaScript:
array.unshift(...array2);array = array.concat(array2)[...array, ...array2] (using the spread operator)Options being compared:
Each option has its own pros and cons:
array.unshift(...array2);: This approach adds elements to the beginning of the array. The main advantage is that it can be more efficient when inserting multiple elements at once, as unshift only creates a new array with the elements in the correct order, without shifting all existing elements. However, this approach can lead to memory allocation overhead for large arrays.array = array.concat(array2): This approach concatenates two arrays and assigns the result back to the original array. The main disadvantage is that it creates a new array object each time, which can be inefficient for large datasets. Additionally, concat may not preserve the original array's properties or methods.[...array, ...array2] (using the spread operator): This approach uses the spread operator to create a new array by copying elements from the original array and adding the elements from the second array. The main advantage is that it creates a shallow copy of the arrays, which can be more efficient in terms of memory allocation. However, this approach may not preserve the original array's properties or methods.Library usage:
None of the provided options rely on any external libraries.
Special JS features/syntax:
The spread operator ([...array, ...array2]) is used to create a new array by spreading elements from an existing array. This feature was introduced in ECMAScript 2015 (ES6) as part of the syntax.
Other alternatives:
Some alternative approaches for adding elements to an array include:
push or splice: These methods add elements to the end or at a specific position in the array, respectively.Array.prototype.set: This method sets all elements in an array to new values (not applicable in this case).Array.prototype.slice and concat: While not exactly the same as using push or splice, these methods can achieve similar results.It's worth noting that the choice of approach depends on the specific use case, such as performance requirements, memory constraints, or desired behavior.
