Substrate

@studnicky/v8/array-splice-outside-loops ​

Disallows Array.prototype.splice when it executes once per iteration of a loop keyword or a built-in per-element iteration callback. Each splice shifts the elements after its cut point, making one call O(n) and repeated calls quadratic. The rule resolves the standard-library signature, so computed access is covered and same-named user methods are not.

A deferred callback defined inside a loop is not reported merely because of its lexical location: a non-iteration function boundary stops the per-iteration analysis. For example, data.splice(0, 1) inside a network-response callback passed to fetchThen is not reported even when that call sits inside a for...of, because the callback runs once per response, not once per loop iteration. Build the retained collection with filter or another out-of-place operation instead of repeatedly removing elements.

Fixable: No · Options: No · Suggested severity: error

✗ Incorrect ​

ts
for (let index = items.length - 1; index >= 0; index -= 1) {
  if (!items[index]?.active) {
    items.splice(index, 1);
  }
}
ts
items.forEach((item) => {
  if (item.stale) {
    items.splice(items.indexOf(item), 1);
  }
});

✓ Correct ​

ts
const activeItems = items.filter((item) => item.active);
ts
const staleIds = new Set(idsToRemove);
const retained = records.filter((record) => !staleIds.has(record.id));