Salesforce Component Quality Standards

Apply these checks to every LWC, Aura component, and Visualforce page you write or review.

Section 1 — LWC Quality Standards

1.1 Data Access Pattern Selection

Choose the right data access pattern before writing JavaScript controller code:

Use case	Pattern	Why
Read a single record reactively (follows navigation)	`@wire(getRecord, { recordId, fields })`	Lightning Data Service — cached, reactive
Standard CRUD form for a single object	`<lightning-record-form>` or `<lightning-record-edit-form>`	Built-in FLS, CRUD, and accessibility
Complex server query or filtered list	`@wire(apexMethodName, { param })` on a `cacheable=true` method	Allows caching; wire re-fires on param change
User-triggered action, DML, or non-cacheable server call	Imperative `apexMethodName(params).then(...).catch(...)`	Required for DML — wired methods cannot be `@AuraEnabled` without `cacheable=true`
Cross-component communication (no shared parent)	Lightning Message Service (LMS)	Decoupled, works across DOM boundaries
Multi-object graph relationships	GraphQL `@wire(gql, { query, variables })`	Single round-trip for complex related data

1.2 Security Rules

Rule	Enforcement
No raw user data in `innerHTML`	Use `{expression}` binding in the template — the framework auto-escapes. Never use `this.template.querySelector('.el').innerHTML = userValue`
Apex `@AuraEnabled` methods enforce CRUD/FLS	Use `WITH USER_MODE` in SOQL or explicit `Schema.sObjectType` checks
No hardcoded org-specific IDs in component JavaScript	Query or pass as a prop — never embed record IDs in source
`@api` properties from parent: validate before use	A parent can pass anything — validate type and range before using as a query parameter

1.3 SLDS 2 and Styling Standards

Never hardcode colours:

color: #FF3366

→ use

color: var(--slds-c-button-brand-color-background)

or a semantic SLDS token.

Never override SLDS classes with
```
!important
```
— compose with custom CSS properties.

Use

<lightning-*>

base components wherever they exist:

lightning-button

lightning-input

lightning-datatable

lightning-card

, etc.

Base components include built-in SLDS 2, dark mode, and accessibility — avoid reimplementing their behaviour.
If using custom CSS, test in both light mode and dark mode before declaring done.

1.4 Accessibility Requirements (WCAG 2.1 AA)

Every LWC component must pass all of these before it is considered done:

All form inputs have
```
<label>
```
or
```
aria-label
```
— never use placeholder as the only label
All icon-only buttons have
```
alternative-text
```
or
```
aria-label
```
describing the action
All interactive elements are reachable and operable by keyboard (Tab, Enter, Space, Escape)
Colour is not the only means of conveying status — pair with text, icon, or
```
aria-*
```
attributes
Error messages are associated with their input via
```
aria-describedby
```
Focus management is correct in modals — focus moves into the modal on open and back on close

1.5 Component Communication Rules

Direction	Mechanism
Parent → Child	`@api` property or calling a `@api` method
Child → Parent	`CustomEvent` — `this.dispatchEvent(new CustomEvent('eventname', { detail: data }))`
Sibling / unrelated components	Lightning Message Service (LMS)
Never use	`document.querySelector` , `window.*` , or Pub/Sub libraries

For Flow screen components:

Events that need to reach the Flow runtime must set
```
bubbles: true
```
and
```
composed: true
```
.
Expose
```
@api value
```
for two-way binding with the Flow variable.

1.6 JavaScript Performance Rules

No side effects in
connectedCallback
: it runs on every DOM attach — avoid DML, heavy computation, or rendering state mutations here.
Guard
renderedCallback
: always use a boolean guard to prevent infinite render loops.
Avoid reactive property traps: setting a reactive property inside
```
renderedCallback
```
causes a re-render — use it only when necessary and guarded.
Do not store large datasets in component state — paginate or stream large results instead.

1.7 Jest Test Requirements

Every component that handles user interaction or retrieves Apex data must have a Jest test:

javascript

// Minimum test coverage expectations
it('renders the component with correct title', async () => { ... });
it('calls apex method and displays results', async () => { ... });  // Wire mock
it('dispatches event when button is clicked', async () => { ... });
it('shows error state when apex call fails', async () => { ... }); // Error path

Use

@salesforce/sfdx-lwc-jest

mocking utilities:

```
wire
```
adapter mocking:
```
setImmediate
```
+
```
emit({ data, error })
```

Apex method mocking:

jest.mock('@salesforce/apex/MyClass.myMethod', ...)

Section 2 — Aura Component Standards

2.1 When to Use Aura vs LWC

New components: always LWC unless the target context is Aura-only (e.g. extending
```
force:appPage
```
, using Aura-specific events in a legacy managed package).
Migrating Aura to LWC: prefer LWC, migrate component-by-component; LWC can be embedded inside Aura components.

2.2 Aura Security Rules

```
@AuraEnabled
```
controller methods must declare
```
with sharing
```
and enforce CRUD/FLS — Aura does not enforce them automatically.
Never use
```
{!v.something}
```
with unescaped user data in
```
<div>
```
unbound helpers — use
```
<ui:outputText value="{!v.text}" />
```
or
```
<c:something>
```
to escape.
Validate all inputs from component attributes before using them in SOQL / Apex logic.

2.3 Aura Event Design

Component events for parent-child communication — lowest scope.
Application events only when component events cannot reach the target — they broadcast to the entire app and can be a performance and maintenance problem.
For hybrid LWC + Aura stacks: use Lightning Message Service to decouple communication — do not rely on Aura application events reaching LWC components.

Section 3 — Visualforce Security Standards

3.1 XSS Prevention

xml

<!-- ❌ NEVER — renders raw user input as HTML -->
<apex:outputText value="{!userInput}" escape="false" />

<!-- ✅ ALWAYS — auto-escaping on -->
<apex:outputText value="{!userInput}" />
<!-- Default escape="true" — platform HTML-encodes the output -->

Rule:

escape="false"

is never acceptable for user-controlled data. If rich text must be rendered, sanitise server-side with a whitelist before output.

3.2 CSRF Protection

Use

<apex:form>

for all postback actions — the platform injects a CSRF token automatically into the form. Do not use raw

<form method="POST">

HTML elements, which bypass CSRF protection.

3.3 SOQL Injection Prevention in Controllers

apex

// ❌ NEVER
String soql = 'SELECT Id FROM Account WHERE Name = \'' + ApexPages.currentPage().getParameters().get('name') + '\'';
List<Account> results = Database.query(soql);

// ✅ ALWAYS — bind variable
String nameParam = ApexPages.currentPage().getParameters().get('name');
List<Account> results = [SELECT Id FROM Account WHERE Name = :nameParam];

3.4 View State Management Checklist

View state is under 135 KB (check in browser developer tools or the Salesforce View State tab)
Fields used only for server-side calculations are declared
```
transient
```
Large collections are not persisted across postbacks unnecessarily
```
readonly="true"
```
is set on
```
<apex:page>
```
for read-only pages to skip view-state serialisation

3.5 FLS / CRUD in Visualforce Controllers