I am exploring different ways to create arrays in JavaScript and would like to understand the fundamental differences between two methods. I am also interested in knowing if there is a performance gap between these two "styles"
var array_1 = new Array("fee","fie","foo","fum");
var array_2 = ['a','b','c'];
for (let i=0; i<array_1.length; i++){
console.log(array_1[i])
}
for (let i=0; i<array_2.length; i++){
console.log(array_2[i])
}
Both notations achieve the same result. Here are some advantages of using the [] notation:
Array symbol, it will still work.new Array(3), it could be misinterpreted as [3]. In reality, it creates an array with a length of 3 and no entries.Array symbol like new Array does. However, this difference is unlikely to have a significant impact in normal use cases.Overall, there are several reasons to choose [].
On the other hand, here are some advantages of using new Array:
var a = new Array(3);However, I personally haven't found a need for this approach in years, especially after realizing that arrays aren't true arrays and pre-allocation is unnecessary. If needed, you can always achieve the same result by doing this instead:
var a = [];
a.length = 3;
When it comes to how you use them, there is no distinction.
The main variation in usage lies in providing an integer parameter to new Array(), which establishes the initial length of the array (something that cannot be achieved with the [] array-literal notation). Nevertheless, both methods create identical objects for your specific scenario.
The comparison on JSPerf between array literal form and constructor reveals that the former tends to be quicker on certain browsers without being slower on any.
It's important to note that this performance discrepancy is specific to different browser implementations, so it's recommended to conduct your own tests on your target platforms.
In my opinion, the advantages of performance are insignificant.
In my opinion, the performance of both methods is comparable since they ultimately result in the creation of an "Array object". Once you begin utilizing the array, the operational mechanism remains unchanged. While I am uncertain about the variance in construction mechanisms for the arrays (in terms of performance), it is unlikely that there would be any significant advantages in using one approach over the other.
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