SALESFORCE-PD1 User Interface Practice Test 6 — 15 Questions

Question 1

Which TWO conditions must be met for an Apex method to be wired using the @wire service in an LWC? Choose 2 answers.

Accepted Answer

The Apex method must be public or global and static.. Option B is correct because an Apex method exposed to Lightning Web Components via @wire must be declared public or global and static, since the wire adapter invokes it without an instance context. Option D is correct because the method must be annotated with @AuraEnabled(cacheable=true); the cacheable=true setting is what allows the wire service to call the method and cache its results on the client. Options A, C, and E are incorrect because a wired Apex method does not need to return a DML result, does not need to return a PageReference, and must not be asynchronous via @future — @future methods cannot be wired and cannot be marked cacheable.

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The Apex method must return a DML operation result.

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The Apex method must return a PageReference.

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The Apex method must be asynchronous using @future.

Question 2

Which TWO techniques can be used to pass data from a parent component to a child Lightning Web Component? Choose 2 answers.

Accepted Answer

Calling public @api methods defined on the child component instance from the parent JavaScript.. Data is passed down via public properties decorated with @api or by invoking public child methods.

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Using application events via $A.get('e...')

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Directly modifying child private properties using DOM queries.

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Using global window variables.

Question 3

Which THREE statements are true regarding Lightning Web Component shadow DOM encapsulation? Choose 3 answers.

Accepted Answer

querySelector calls inside a component only search within that component's template unless using specific host selectors.. Option C is correct because Lightning Web Components use native shadow DOM encapsulation, so a component's querySelector/querySelectorAll only traverse that component's own shadow root (its template), and reaching into a child component requires piercing selectors or the child's exposed API rather than ordinary descendant selectors. Option D is correct because each LWC's CSS file is scoped to that component's shadow root, so its rules apply only to elements within that component and do not leak out to the rest of the page. Option E is correct because LWC renders each component's template into a shadow root attached to the component's host element, which is the mechanism that provides the style and DOM encapsulation. Option A is not correct because global stylesheets do not automatically penetrate shadow DOM; they only affect the host element or content explicitly exposed, and styling internals requires styling hooks or ::part. Option B is not correct because a parent cannot directly style a child component's internal elements from its own CSS file; cross-component styling must go through styling hooks (--slds-* custom properties) or exposed parts.

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Global CSS stylesheets automatically penetrate and override LWC shadow DOM styles.

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Child components can be styled directly from parent CSS files without styling hooks.

Question 4

Which TWO actions can a developer perform using standard Visualforce controllers? Choose 2 answers.

Accepted Answer

Perform standard save, delete, and cancel database operations without writing custom Apex code.. Option B is correct because standard Visualforce controllers (such as StandardController) expose built-in save, delete, and cancel actions that automatically handle DML on the associated record, so a developer can wire buttons like <apex:commandButton action="{!save}"/> without writing any custom Apex. Option D is correct because a standard controller binds the Visualforce page to a single sObject record and exposes its fields through merge expressions such as {!Account.Name} or {!Contact.Phone}, letting the page read and display the viewed or edited record's field values. Option A is not correct because standard controllers cannot express custom SQL-like joins or complex multi-object business logic; that requires custom Apex (SOQL/SOSL or Apex controllers). Option C is not correct because standard controllers do not automatically instantiate or invoke web service callouts; callouts must be coded explicitly in Apex. Option E is not correct because overriding standard page layouts is done through configuration (Lightning App Builder, page layout assignment, or Visualforce page overrides), not by a standard controller action.

Answer

Write complex multi-object business logic with custom SQL-like joins.

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Instantiate custom web service callouts automatically.

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Override standard page layouts without any configuration.

Question 5

Which THREE practices are considered security best practices when developing custom Visualforce pages to prevent Cross-Site Scripting (XSS)? Choose 3 answers.

Accepted Answer

Use standard Visualforce components like <apex:outputText> which automatically HTML-escape output by default.. Preventing XSS in Visualforce involves escaping output, using standard components which escape by default, and encoding untrusted data.

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Disable sharing on all controller classes.

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Set escape="false" on all output components to ensure proper rendering.

Question 6

Which THREE requirements must be met when implementing a custom Lightning Web Component pagination control? Choose 3 answers.

Accepted Answer

Slice the master dataset array based on current offset and limit calculations.. Option A is correct because a custom LWC pagination control must compute the visible subset of records by slicing the master dataset array using the current offset (page number × page size) and the page size limit, since LWC has no built-in pagination primitive. Option C is correct because the Next and Previous buttons must be disabled when boundary conditions are reached — Previous at page 1 and Next at the last page — to prevent out-of-range navigation and provide correct UX. Option D is correct because the component must track the current page number and page size as reactive properties (e.g., @track or standard reactive fields) so that changes trigger re-rendering and recomputation of the sliced data. Option B is incorrect because Visualforce's standardSetController is a Visualforce/Apex construct and cannot be used inside LWC JavaScript; pagination in LWC is handled client-side or via Apex methods. Option E is incorrect because mutating the server database on every page click is unnecessary and harmful — pagination should only change the client-side view, not persist data on each navigation.

Answer

Use standard Visualforce standardSetController inside the LWC JavaScript.

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Directly mutate the server database on every page click.

Question 7

Which TWO actions should a developer take when handling errors returned by an imperative Apex call in a Lightning Web Component? Choose 2 answers.

Accepted Answer

Extract the error message from the error object structure (e.g., error.body.message).. Option B is correct because when an imperative Apex call fails, the promise rejects with a JavaScript error object whose useful details live in nested properties such as error.body.message (and error.body.pageErrors or error.body.fieldErrors), so the developer must extract the message from that structure to surface a meaningful error. Option D is correct because imperative Apex calls return a Promise, so errors must be handled by chaining a .catch() handler or by wrapping the call in try/catch when using async/await; otherwise the rejection is unhandled. Option A is wrong because ApexPages.addMessage() is a server-side Apex method for Visualforce pages, not for Lightning Web Components. Option C is wrong because Apex is not Java and rethrowing as an unhandled Java exception is neither possible nor a valid LWC error-handling pattern. Option E is wrong because window.alert() is a blocking browser dialog and is not the recommended way to present errors in a Lightning Web Component, which should use lightning-toast or inline UI instead.

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Call ApexPages.addMessage() to display the error on screen.

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Rethrow the error as an unhandled Java exception.

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Use standard window.alert() for all error messaging.

Question 8

Which THREE strategies are recommended for improving the performance of Lightning Web Components rendering large lists of data? Choose 3 answers.

Accepted Answer

Provide a unique, stable 'key' attribute (such as record Id) on each iterated element in for:each loops.. Option B is correct because giving each iterated element a unique, stable key (e.g., the record Id) in for:each loops lets the Lightning Web Components engine's diffing algorithm track items across re-renders and reuse DOM nodes instead of destroying and recreating them, which dramatically reduces rendering work. Option C is correct because pagination, virtual scrolling, or lazy loading limits the number of rows actually rendered in the DOM at any time, so the browser only paints a small window of records rather than the entire dataset, keeping render and layout times low. Option D is correct because getter properties referenced in a template are re-evaluated on every render cycle, so placing heavy computation or data transformation there multiplies the cost across all rows; moving that logic to one-time initialization or cached properties avoids repeated expensive work. Option A is not recommended because synchronous imperative Apex calls block the client thread and, when invoked inside iterators, can fire one call per row, causing severe latency and governor-limit pressure. Option E is incorrect because rendering all 10,000 records at once in a single flat DOM tree creates an enormous DOM, causing slow initial render, sluggish scrolling, and high memory usage, which is exactly the anti-pattern these strategies are meant to avoid.

Answer

Use synchronous imperative Apex calls inside template iterators.

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Render all 10,000 records at once in a single flat DOM tree without pagination.

Question 9

A developer is building a Lightning Web Component and needs to execute code as soon as the component is inserted into the DOM. Which lifecycle hook should the developer use?

Accepted Answer

connectedCallback(). The connectedCallback() lifecycle hook is called when a component is inserted into the DOM. It is the appropriate place to execute initialization code that requires the component to be in the DOM, such as accessing elements or making network requests. It fires after the constructor but before rendering.

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constructor()

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disconnectedCallback()

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renderedCallback()

Question 10

A developer needs to pass data from a child Lightning Web Component to a parent Lightning Web Component up the component hierarchy. What is the standard mechanism to achieve this?

Accepted Answer

Dispatch a CustomEvent in the child and handle it in the parent's template using an event listener directive.. Child-to-parent communication in LWC is achieved by dispatching a custom event using CustomEvent and listening to it in the parent template.

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Use the @api decorator in the child component to expose a public method that the parent can call directly.

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Publish a message using the Lightning Message Service from the child and subscribe in the parent.

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Mutate a shared global reactive property imported from a common utility JavaScript module.

Question 11

A developer is styling a Lightning Web Component using the Salesforce Lightning Design System (SLDS). To ensure the component adheres to the standard styling guidelines for spacing, what should the developer use?

Accepted Answer

SLDS standard spacing utility classes.. SLDS provides a documented set of spacing utility classes (e.g., slds-m-around_medium, slds-p-horizontal_small) that enforce the design system's standardized spacing scale. Using these utilities guarantees visual consistency across components and future-proofs the UI against SLDS token changes. This is the officially recommended approach for adhering to SLDS styling guidelines.

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Inline styles directly in the HTML template.

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Standard HTML blockquote tags with custom margin properties.

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Hardcoded pixel values in the component's CSS file.

Question 12

A developer has an Aura component that needs to communicate with an unrelated Lightning Web Component located on the same Lightning page. Which feature should the developer implement?

Accepted Answer

Lightning Message Service (LMS). The Lightning Message Service (LMS) allows communication between Visualforce pages, Aura components, and Lightning Web Components across the DOM.

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Aura Component Events (app events)

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A shared JavaScript closure via window globals

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Direct DOM traversal using document.querySelector()

Question 13

A developer needs to ensure that a Lightning Web Component can be placed on a Record Page for an Account in the Lightning App Builder. What must be configured in the component's metadata configuration file?

Accepted Answer

lightning__RecordPage. The target configuration must include lightning__RecordPage and specify the appropriate object support.

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lightning__HomePage

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lightning__Tab

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lightningCommunity__Default

Question 14

A developer is creating a reusable LWC utility and needs to invoke an Apex method imperatively. The method accepts a record ID parameter. What is the correct way to pass this parameter in JavaScript?

Accepted Answer

Pass the parameter as an object with property names matching the Apex method parameters: getAccount({ accountId: recordId }). When invoking an Apex method imperatively from LWC, parameters must be passed as a single object where the keys match the Apex method parameter names exactly. For an Apex method like getAccount(Id accountId), the JavaScript call should be getAccount({ accountId: recordId }). This ensures the correct mapping of values to parameters.

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Pass the parameter as a positional string argument: getAccount({recordId})

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Bind the parameter using the @api decorator inside the JavaScript function body.

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Assign the parameter to the window.apexParams object prior to invocation.

Question 15

A developer is building a Lightning Web Component that includes a custom wire adapter to fetch custom metadata. The wire adapter needs to react whenever a tracked property changes value. How should the developer wire the property?

Accepted Answer

Prefix the parameter passed to the wire adapter with a dollar sign ($) in the JavaScript file.. In LWC, wire adapters are reactive when their parameters are prefixed with '$' in the JavaScript file, which tells the framework to re-invoke the adapter whenever the referenced property changes. For a custom wire adapter that fetches custom metadata, the developer writes something like @wire(getCustomMetadata, { recordId: '$recordId' }) so that changes to recordId automatically re-fire the adapter.

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Wrap the property in a standard JavaScript Proxy object.

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Decorate the parameter with @track and call this.updateWire() explicitly.

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Invoke the refreshApex() method inside the component constructor.