var array = Array.from({length: 10}, (_, index) => index);
var sum = 0
for (var i = 0; i < array.length; i++) {
sum += array[i];
}
var sum = 0
array.forEach(function(item) {
sum += item;
});
var sum = 0
for (var item of array) {
sum += item;
}
var sum = 0
for (var i = array.length; i--;) {
sum += array[i];
}
--enable-precise-memory-info
flag.
Test case name | Result |
---|---|
for | |
forEach | |
for-of | |
for-reverse |
Test name | Executions per second |
---|---|
for | 42409064.0 Ops/sec |
forEach | 60335220.0 Ops/sec |
for-of | 81751888.0 Ops/sec |
for-reverse | 52530820.0 Ops/sec |
The provided JSON represents a JavaScript microbenchmark test case, specifically comparing the performance of four different loop constructs: traditional for
, forEach
, for-of
, and for-reverse
. Let's dive into each option:
Traditional for
Loop
i
) to iterate over the array.forEach
Loop
forEach
method is a part of the Array prototype, which allows you to execute a callback function for each element in an array.forEach
methodfor-of
Loop
for-of
loop is a new iteration of the traditional for
loop, introduced in ECMAScript 2015 (ES6). It allows you to iterate over arrays without declaring an explicit counter variable.for
loopsfor
loops on modern browsersfor-reverse
Loop
for
loop but iterates over the array elements in reverse order.In terms of special JavaScript features, there are no explicit mentions of features like let
, const
, or arrow functions, which may have been used in some of the benchmark definitions.
The test case uses the built-in Array.prototype.forEach
method, which is a part of the Array prototype. This method is designed to iterate over array elements and execute a callback function for each element.
Some considerations when choosing between these loop constructs:
for
loop might be faster due to its lack of overhead.forEach
loop is generally more concise and readable than the traditional for
loop.for-of
loop requires modern browsers (though widely supported in recent versions).Other alternatives for these loop constructs:
while
loops or recursive functionsmap
, filter
, or reduce
Array.prototype.reduce()
or other higher-order functionsKeep in mind that the performance differences between these loop constructs may be relatively small, and the choice ultimately depends on your specific use case, personal preference, and code readability goals.