Application Development - 2 · Quiz 1 · Jan 2026

**1. Compare scope boundaries:** var is scoped to its containing function or script, rather than an ordinary brace block. let and const introduce block-scoped bindings. **2. Distinguish creation from initialization:** let is unavailable in its temporal dead zone before initialization; const requires an initializer in an ordinary declaration. Top-level let/const bindings do not automatically become window properties. **Answer: A, B — A and B.** A: **Correct:** var does not gain a new scope from a normal block inside a function. B: **Correct:** Both keywords respect block scope. C: **Incorrect:** let bindings exist before their declaration but are not initialized to undefined during the temporal dead zone. D: **Incorrect:** An ordinary const declaration without an initializer is a syntax error. E: **Incorrect:** Global lexical let/const bindings are not window properties.

**1. Identify function objects and declarations:** JavaScript functions are callable objects. Function declarations are instantiated before ordinary execution of their containing scope. **2. Compare arrows and expressions:** Arrows capture lexical this. A function expression is evaluated when its assignment executes; only its variable binding may be created earlier, without that function value. **Answer: A, C — A and C.** A: **Correct:** Functions are objects with callable behavior. B: **Incorrect:** An arrow inherits this rather than creating its own receiver binding. C: **Correct:** Ordinary function declarations are available before their source position in the containing scope. D: **Incorrect:** The function-expression value is not assigned until execution reaches the expression.

**1. Read the explicit receiver:** obj1.show.apply(obj1) invokes show with this equal to obj1. **2. Resolve the property:** this.a is therefore obj1.a=20. Neither obj2.a=10 nor the global a=3 is used. **Answer: A — 20.** A: **Correct:** The explicit receiver obj1 has a=20. B: **Incorrect:** obj2 is not passed to apply. C: **Incorrect:** The receiver has the requested property a. D: **Incorrect:** The function reads this.a rather than the global identifier a.

**1. Start with an empty stored cart:** The first load passes the name property "Laptop", not the whole object, into addItemToCart. It parses the previous JSON, pushes the name, and saves the updated JSON. **2. Count loads:** Initial loading plus two refreshes executes the push three times. localStorage survives these reloads, leaving three copies of Laptop. **3. Identify the returned type:** getCartItems returns localStorage.getItem directly, so the logged value is the JSON string ["Laptop","Laptop","Laptop"]. B shows the intended three-item content. **Answer: B — Three Laptop names: ["Laptop","Laptop","Laptop"].** **Convention note:** This assumes cart was absent before the initial load. The precise logged JavaScript value is a JSON string, not an array, because getCartItems omits JSON.parse; B is the intended content match. A: **Incorrect:** An item is appended on every load. B: **Correct:** It shows the three Laptop names accumulated across three executions. C: **Incorrect:** The function receives only .name, and the code runs three times rather than once. D: **Incorrect:** The .name expression is defined and equals Laptop.

**1. Match storage lifetime and purpose:** Session storage belongs to a browser-tab session, matching B. Token storage describes retaining authentication tokens, matching C. **2. Match cookies:** Cookies can persist across sessions when configured with an expiry and are attached automatically to applicable HTTP requests, matching D. None of these mechanisms inherently encrypts stored values as A claims. **Answer: D — 1→B, 2→C, 3→D.** **Convention note:** “Token storage” is a purpose, not a distinct browser API or a guarantee of security. Cookie persistence depends on expiry settings; transmission depends on domain/path, Secure, SameSite and request credentials. A: **Incorrect:** Cookie storage does not automatically encrypt its contents. B: **Incorrect:** Session and token characteristics are mismatched, and automatic encryption is not inherent. C: **Incorrect:** Session storage is not automatically encrypted and cookie storage is not defined merely as token storage. D: **Correct:** It gives Session→B, Token→C and Cookie→D.

**1. Pop datasets in reverse order:** The first three timer ticks consume (5000,30,4), then (3000,20,3), then (2000,10,2). Simple interest is \(P r t/100\). **2. Add the computed interest values:** They are 6000,1800,400, so totalPayableAmount becomes \(6000+1800+400=8200\). The computed property is recalculated from the updated reactive inputs. **3. Check the fourth tick:** The array is now empty; pop() returns undefined and accessing data[0] throws before another sum is added. The existing displayed total remains 8200. **Answer: B — total payable amount is 8200.** **Convention note:** The interval is not cleared when appData becomes empty, so it causes an error at the fourth tick. That error does not erase the previously rendered total. “After 4 seconds” assumes the successful timer updates have run normally. A: **Incorrect:** 6000 is the total after only the first tick. B: **Correct:** The three successful updates sum to 8200. C: **Incorrect:** 1800 is only the second tick’s interest. D: **Incorrect:** It includes the first two increments but omits the final 400.

**1. Follow the prototype:** The object-literal __proto__:course sets student’s prototype to course, where courseName is defined. **2. Destructure through ordinary property access:** Reading student.courseName can find an inherited property. The courseName binding therefore receives "Modern Application Development 2". **Answer: B — Modern Application Development 2.** A: **Incorrect:** Inherited properties are available to ordinary property access and destructuring. B: **Correct:** The lookup reaches course.courseName through the prototype. C: **Incorrect:** The object-literal prototype setter and destructuring syntax are valid. D: **Incorrect:** The listed course-name output is correct.

**1. Separate the bindings:** op(x) declares a parameter named x, which shadows the outer let x=2. Both op() calls pass no argument, so each local parameter begins as undefined. **2. Evaluate only the local arithmetic:** undefined×3 becomes NaN; adding 4 and subtracting 1 keep NaN. No assignment touches the outer binding. **3. Read the final outer value:** console.log(x) therefore prints 2. **Answer: 2.**

**1. Define ephemeral UI state:** It describes short-lived interface conditions, such as whether a request is loading, which tab is selected or whether a menu is open. It is usually local to a view rather than permanent domain data. **Answer: C — It refers to short-lived interface elements like loading indicators or selected .** A: **Incorrect:** Permanent shared database records are domain/application data. B: **Incorrect:** Users, products and transactions describe longer-lived system data. C: **Correct:** Loading indicators and selected tabs are standard short-lived UI state. D: **Incorrect:** This concerns broader application/session concerns rather than ephemeral interface conditions.

**1. Interpret stateless HTTP:** A request does not automatically carry conversational state from a preceding request. **2. Carry context explicitly:** Clients can send a session cookie, token or other identifier; the server can retrieve stored state, or the client can send the needed data directly. State is managed by the application and exchanged in requests. **Answer: C — Client or server maintaining state and explicitly exchanging it through .** A: **Incorrect:** Frontend memory alone does not persist through closing or reloading the application. B: **Incorrect:** Client-side logic alone does not explain client–server state continuity. C: **Correct:** It explicitly communicates the context needed to associate separate requests. D: **Incorrect:** Stateless transport does not require stateless applications.

**1. Create separate closures:** Each outer() invocation creates its own count=0. c1 and c2 therefore retain independent counters. **2. Apply postfix increment:** return count++ returns the old value, then increments. The first two c1 calls return 0 then 1; the first c2 call returns its separate initial value 0. **Answer: D — 0, 1, 0.** A: **Incorrect:** This would correspond to prefix increment rather than the shown postfix increment. B: **Incorrect:** The second c1 call observes its retained incremented state. C: **Incorrect:** c2 has a separate counter and does not continue c1’s count. D: **Correct:** The outputs are 0,1,0.

**1. Fill the complete slot:** No parent content targets the named complete slot, so its fallback heading Learned DBMS is displayed. **2. Fill the default slot:** The ordinary parent heading supplies Exploring Vue Js, replacing the default fallback Exploring Frontend. **3. Check the last-slot syntax:** The parent incorrectly places v-slot:last on a slot element rather than a template or component. It does not provide a usable last-slot heading to this child; the displayed headings are Learned DBMS and Exploring Vue Js. **Answer: C — Learned DBMS; Exploring Vue Js.** **Convention note:** The slot element bearing v-slot:last is invalid slot-provision syntax and can generate a compiler warning. Proper named-slot provision uses a template with v-slot:last; the question’s key excludes the attempted last heading. A: **Incorrect:** Exploring Backend is not supplied by either the component or parent. B: **Incorrect:** This is Last Course is not provided by the code. C: **Correct:** It shows the complete-slot fallback followed by the parent’s default-slot heading. D: **Incorrect:** C matches the intended rendered headings.

**1. Create and increment the shared count:** createCounter(3) sets start=count=3. counter(2) takes the numeric branch, making count=5 and returning a=5. **2. Capture temp in the returned inner function:** counter() receives undefined, takes the nonnumeric branch and captures temp=5. Its returned function is immediately invoked with true, resetting count to the original start=3. **3. Add the results:** That invocation returns d=temp+count=5+3=8. The final expression is a+d=5+8=13. **Answer: B — 13.** **Convention note:** The last line evaluates a+d but does not explicitly call console.log. A browser console displays 13 as the expression result; an ordinary script would produce no printed log from that line alone. A: **Incorrect:** 5 is only a, not the final sum. B: **Correct:** The shared reset gives d=8, so the sum is 13. C: **Incorrect:** 8 is only d, not a+d. D: **Incorrect:** It does not account for the captured temp=5 plus reset count=3.

**1. Evaluate the methods on their instances:** d.info() reads type="Electronic" and returns Electronic device. m.info() uses its override, reading brand="Samsung" and type="Electronic", returning Samsung is a Electronic device. **2. Detach the method:** x=m.info stores the function without binding m. Class methods run in strict mode; plain x() has this=undefined and throws TypeError on this.brand. **3. Distinguish a constructor from an instance method:** d.constructor refers to class Device. Calling a class as an ordinary function without new throws; it does not return info text. **Answer: A, B, C — A, B and C.** A: **Correct:** The base instance’s info method returns the stated text. B: **Correct:** The subclass override uses the stored brand and type. C: **Correct:** The detached class method loses its instance receiver and throws TypeError. D: **Incorrect:** Class constructors cannot be invoked as ordinary functions to obtain an info string.

**1. Locate beforeMount:** Vue has prepared its rendering machinery but has not yet patched the mounted DOM. The original in-document p element still exists with its literal interpolation text. **2. Distinguish data from DOM:** Changing message to Start A inside beforeMount changes component data before the initial render, but the original DOM is not already showing that rendered value during this hook. **Answer: A — The original p element exists and still contains {{ message }}.** A: **Correct:** The original in-DOM template element still contains the interpolation before the initial patch. B: **Incorrect:** Start A appears after rendering/patching, not already at entry to beforeMount. C: **Incorrect:** mounted runs after the initial mount, later than beforeMount. D: **Incorrect:** The initial HTML elements exist even though Vue has not patched them yet.

**1. Update data before initial rendering:** beforeMount appends " A" to message, changing Start into Start A. The initial render therefore writes Start A into the p element. **2. Apply the mounted hook’s direct DOM change:** It reads that text and appends " DOM", producing Start A DOM. **3. Check for further reactive changes:** mounted changes innerText, not message. With no subsequent reactive update, the displayed text stays Start A DOM. **Answer: D — Start A DOM.** A: **Incorrect:** It omits the mounted hook’s explicit DOM suffix. B: **Incorrect:** The code never appends B. C: **Incorrect:** The code never appends B before the DOM suffix. D: **Correct:** It includes the beforeMount A suffix and mounted DOM suffix.