Why is the first loop implementation more performant?
function processItems(items) {
const len = items.length;
for (let i = 0; i < len; i++) {
// Process item
}
}
function processItemsSlow(items) {
for (let i = 0; i < items.length; i++) {
// Process item
}
}
Caching array length improves performance by: 1) Avoiding repeated property access on each iteration, 2) Array length lookup requires property resolution each time, 3) Cached length value is accessed from a local variable which is faster, 4) Particularly important for large arrays or hot loops, 5) Local variable access is optimized by JavaScript engines, 6) Reduces the number of operations in the loop condition, 7) This optimization can significantly improve loop performance, 8) A fundamental optimization technique for array operations.