var array = [new Array(1000)];
for (var i = 0; i < array.length; i++) {
array[i];
}
array.forEach(function(i) {
array[i];
});
array.some(function(i) {
array[i];
});
for (var i of array) {
array[i];
}
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
for | |
foreach | |
some | |
for..of |
Test name | Executions per second |
---|---|
for | 2457.3 Ops/sec |
foreach | 4066.0 Ops/sec |
some | 3974.2 Ops/sec |
for..of | 4411.7 Ops/sec |
Let's dive into the provided benchmark definition and test cases.
Benchmark Definition
The provided JSON represents a JavaScript microbenchmarking tool called MeasureThat.net. The benchmark compares the performance of four different loop types:
for
loopforEach
loop (array iteration)some
loop (array iteration with early exit)for..of
loop (array iteration with automatic index)The benchmark uses a fixed array size of 1000 elements, which is pre-created using the "Script Preparation Code".
Loop Options Compared
Here's a brief overview of each loop option:
for
loop: This is the most basic type of loop. It uses an incrementing index variable to access array elements.forEach
loop (array iteration): Introduced in ECMAScript 2015, this loop type is designed for iterating over arrays. It uses a callback function to process each element.for
loops, as it avoids manual indexing and incrementing.forEach
method.some
loop (array iteration with early exit): Another ECMAScript 2015 feature, this loop type is similar to forEach
, but returns a boolean value indicating whether any element passed the condition.for
loops for large arrays, as it can stop iterating early if no elements match the condition.some
method.for..of
loop (array iteration with automatic index): Introduced in ECMAScript 2015, this loop type is designed for iterating over arrays. It uses an iterator object to access array elements and automatically increments the index variable.for..of
syntax.Library Used
The benchmark uses no external libraries. It relies solely on built-in JavaScript features to execute the loops.
Special JS Features or Syntax
The benchmark uses several ES2015/ES2017 features, including:
forEach
: Introduced in ECMAScript 2015.some
: Introduced in ECMAScript 2015.for..of
: Introduced in ECMAScript 2015.These features are widely supported by modern browsers and are a good indication of the benchmark's compatibility with current JavaScript versions.
Other Alternatives
If the for
, forEach
, or some
loops were not available, alternative loop types could have been used. Some examples include:
while
loop: A more low-level approach that requires manual indexing and incrementing.However, these alternatives would likely incur additional overhead due to the need for manual indexing and incrementing, making them less efficient than the compared loop types.