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small-rules

No New Instance In Use Memo

Error
small-rules/no-new-instance-in-use-memo

Disallow configured constructor calls (default: new Instance) inside React useMemo callbacks.

Diagnostic Messages

noNewInUseMemo
Avoid creating '{{constructorName}}' with `new` inside useMemo. Create it outside the memo callback or use an effect/ref pattern.

Configuration

This rule accepts one options object after the severity.

constructorsOptional

Constructor identifiers that should be disallowed inside useMemo callbacks.

Type
Array<string>
Default
environmentOptional

The React environment: 'roblox-ts' uses @rbxts/react, 'standard' uses react.

Type
"roblox-ts" | "standard"
Default
roblox-ts
maxHelperTraceDepthOptional

Maximum depth for tracing local helper function calls from useMemo callbacks. 0 disables helper traversal.

Type
integer
Default
4
{
  "jsPlugins": [
    "@pobammer-ts/small-rules"
  ],
  "rules": {
    "small-rules/no-new-instance-in-use-memo": [
      "error",
      {
        "constructors": [
          "Instance"
        ],
        "environment": "roblox-ts",
        "maxHelperTraceDepth": 4
      }
    ]
  }
}

Examples

New instance inside memo
import { useMemo } from "@rbxts/react";


const model = useMemo(() => {
    return new Instance("Model");
}, []);
Non-React memo function
function useMemo(factory) {
    return factory();
}


const model = useMemo(() => new Instance("Model"), []);
No Useless Use MemoRelatedMemoizing Instance construction is a Roblox-specific useMemo correctness concern.