salesforce-component-standards

name salesforce-component-standards description Quality standards for Salesforce Lightning Web Components (LWC), Aura components, and Visualforce pages. Covers SLDS 2 compliance, accessibility (WCAG 2.1 AA), data access pattern selection, component communication rules, XSS prevention, CSRF enforcement, FLS/CRUD in AuraEnabled methods, view state management, and Jest test requirements. Use this skill when building or reviewing any Salesforce UI component to enforce platform-specific security and quality standards. 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: // 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 <!-- ❌ 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 // ❌ 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 // Before reading a field if (!Schema.sObjectType.Account.fields.Revenue__c.isAccessible()) { ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.ERROR, 'You do not have access to this field.')); return null; } // Before performing DML if (!Schema.sObjectType.Account.isDeletable()) { throw new System.NoAccessException(); } Standard controllers enforce FLS for bound fields automatically. Custom controllers do not — FLS must be enforced manually. Quick Reference — Component Anti-Patterns Summary Anti-pattern Technology Risk Fix innerHTML with user data LWC XSS Use template bindings {expression} Hardcoded hex colours LWC/Aura Dark-mode / SLDS 2 break Use SLDS CSS custom properties Missing aria-label on icon buttons LWC/Aura/VF Accessibility failure Add alternative-text or aria-label No guard in renderedCallback LWC Infinite rerender loop Add hasRendered boolean guard Application event for parent-child Aura Unnecessary broadcast scope Use component event instead escape="false" on user data Visualforce XSS Remove — use default escaping Raw <form> postback Visualforce CSRF vulnerability Use <apex:form> No with sharing on custom controller VF / Apex Data exposure Add with sharing declaration FLS not checked in custom controller VF / Apex Privilege escalation Add Schema.sObjectType checks SOQL concatenated with URL param VF / Apex SOQL injection Use bind variables