Always use optional chaining (`?.`) and nullish coalescing (`??`) operators when accessing potentially undefined or null properties. These patterns prevent TypeErrors when accessing nested properties and provide appropriate defaults only when values are null or undefined.
Always use optional chaining (?.) and nullish coalescing (??) operators when accessing potentially undefined or null properties. These patterns prevent TypeErrors when accessing nested properties and provide appropriate defaults only when values are null or undefined.
// Unsafe - may throw TypeError:
const message = runData.data[NodeConnectionTypes.Main][0][0].evaluationData;
const activeModules = [...settings.value.activeModules, 'data-store'];
const isMFAEnforced = settings.value.enterprise.mfaEnforcement;
// Safe - uses proper null handling:
const message = runData?.data?.[NodeConnectionTypes.Main]?.[0]?.[0]?.evaluationData ?? {};
const activeModules = [...(settings.value.activeModules ?? []), 'data-store'];
const isMFAEnforced = settings.value.enterprise?.mfaEnforcement ?? false;
When handling arrays from potentially empty sources, provide empty array defaults and filter out falsy values:
// Handle empty split results with proper filtering
const selectedApps = currentUserCloudInfo.value?.selectedApps?.split(',').filter(Boolean) ?? [];
// Check object existence before property access
if (toolOrToolkit && typeof (toolOrToolkit as Toolkit).getTools === 'function') {
// Now safe to call the method
}
// Use proper object access patterns to avoid null reference errors
const hasNodeRun = Object.prototype.hasOwnProperty.call(runData ?? {}, node.name);
Always ensure your type definitions accurately represent nullable values. If an API can return null for a field, include it in the type:
// Accurate type for a field that can be null
interface Response {
stop_reason: string | null;
}
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