BTW, DOWNLOAD part of GetValidTest JS-Dev-101 dumps from Cloud Storage: https://drive.google.com/open?id=1AsP_YQaWdrC66hgpZcDWGKBtTLoDLhGN
You can first download GetValidTest's free exercises and answers about Salesforce certification JS-Dev-101 exam as a try, then you will feel that GetValidTest give you a reassurance for passing the exam. If you choose GetValidTest to provide you with the pertinence training, you can easily pass the Salesforce Certification JS-Dev-101 Exam.
| Section | Weight | Objectives |
|---|---|---|
| Browser and Events | 17% | - Event handling, propagation, listeners - DOM selection and manipulation - Browser APIs and developer tools |
| Testing | 7% | - Unit test structure and effectiveness - Test coverage and improvement |
| Variables, Types, and Collections | 23% | - Strings, numbers, dates, arrays and methods - Variable declaration and scope - Data types, type coercion, truthy/falsy values - JSON parsing and manipulation |
| Asynchronous Programming | 13% | - Event loop and execution flow - Callbacks, promises, async/await |
| Debugging and Error Handling | 7% | - Error types and handling strategies - Console usage, breakpoints and debugging techniques |
| Objects, Functions, and Classes | 25% | - Object creation, properties, prototypes - ES6 classes, inheritance, modules, decorators - Function types, scope, closures, arrow functions |
| Server Side JavaScript | 8% | - Node.js fundamentals and core modules - Package management and CLI tools |
>> Exam JS-Dev-101 Pass Guide <<
Everyone has different learning habits, JS-Dev-101 exam simulation provide you with different system versions: PDF version, Software version and APP version. Based on your specific situation, you can choose the version that is most suitable for you, or use multiple versions at the same time. After all, each version of JS-Dev-101 Preparation questions have its own advantages. If you are very busy, you can only use some of the very fragmented time to use our JS-Dev-101 study materials. And each of our JS-Dev-101 exam questions can help you pass the exam for sure.
NEW QUESTION # 87
A developer writes the code below to return a message to a user attempting to register a new username. If the username is available, a variable named nag is declared and assigned a value on line 03.
What is the value of msg when getAvailableabilityMessage ("newUserName") is executed and get Availability ("newUserName") returns true?
Answer: D
NEW QUESTION # 88
Refer to the code below:
01 function changeValue(param) {
02 param = 5;
03 }
04 let a = 10;
05 let b = a;
06
07 changeValue(b);
08 const result = a + ' - ' + b;
What is the value of result when the code executes?
Answer: A
Explanation:
We must understand pass-by-value for primitives in JavaScript.
Initial values:
let a = 10;
let b = a; // b gets a copy of the value 10
So:
a is 10
b is 10 (independent copy)
Function call:
changeValue(b);
Function definition:
function changeValue(param) {
param = 5;
}
param receives the value of b, which is 10.
Inside the function, param is a local variable.
param = 5; changes only this local copy.
It does not affect b outside the function.
After the function call:
a is still 10.
b is still 10.
Result:
const result = a + ' - ' + b;
a is 10.
b is 10.
String concatenation: '10 - 10'.
So result is:
"10 - 10"
Therefore, the correct option is:
Study Guide Concepts:
Primitive values (numbers, strings, booleans) are passed by value
Function parameters as local variables
String concatenation with +
Difference between mutating references vs primitives
NEW QUESTION # 89
A Node.js server library uses events and callbacks. The developer wants to log any issues the server has at boot time.
Which code logs an error with an event?
Answer: B
Explanation:
console.log('ERROR', error);
}
Explanation:
Node.js event-based modules use the EventEmitter pattern.
The correct syntax for listening to events is:
emitter.on('eventName', callback)
The server library emits an 'error' event, which must be listened to using .on.
Option analysis:
A: .catch is for Promises, not EventEmitters.
B: .error is not an EventEmitter method.
C: Correct. Listens to the 'error' event.
D: try...catch only captures synchronous errors, not event-based asynchronous errors.
Therefore, the correct answer is option C.
JavaScript Knowledge Reference (text-only)
The EventEmitter API uses on(event, handler) to listen for events.
Errors emitted asynchronously cannot be caught with try...catch.
The 'error' event is standard for Node.js modules to signal operational errors.
NEW QUESTION # 90
A developer has code that calculates a restaurant bill, but generates incorrect answers while testing the code:
function calculateBill (items ) {
let total = 0;
total += findSubTotal(items);
total += addTax(total);
total += addTip(total);
return total;
}
Which option allows the developer to step into each function execution within calculateBill?
Answer: B
NEW QUESTION # 91
Refer to the code below:
01 async function functionUnderTest(isOK) {
02 if (isOK) return 'OK';
03 throw new Error('not OK');
04 }
Which assertion accurately tests the above code?
Answer: A
Explanation:
The function:
async function functionUnderTest(isOK) {
if (isOK) return 'OK';
throw new Error('not OK');
}
Behavior:
If isOK is true:
The function resolves (fulfills the promise) with value 'OK'.
If isOK is false:
The function throws, which in an async function becomes a rejected promise with Error('not OK').
We want an assertion that accurately tests the successful path for isOK === true.
Key points about console.assert:
Signature: console.assert(condition, message?)
If condition is falsy, it logs message as an assertion failure.
If condition is truthy, nothing is logged.
We also must understand await:
await functionUnderTest(true) will resolve to the string 'OK'.
Now evaluate options.
Option A:
console.assert(await functionUnderTest(true), 'OK');
await functionUnderTest(true) β 'OK' (truthy).
console.assert('OK', 'OK');
Condition is 'OK' (truthy), so assertion passes.
The message 'OK' is only shown if the condition is falsy, which it is not.
This correctly verifies that the promise resolved (i.e., did not reject). Among the given options, this is the only one that both:
Uses await properly on the async function, and
Associates the message with the expected success "OK".
Option B:
console.assert(await (functionUnderTest(true), 'not OK'));
Inside the parentheses, the comma operator (a, b) evaluates a, discards it, and returns b.
So (functionUnderTest(true), 'not OK'):
Calls functionUnderTest(true) (returns a promise, but its result is discarded), The expression evaluates to the string 'not OK'.
Then await 'not OK' just resolves to 'not OK' immediately (not a promise).
console.assert('not OK');
Condition is 'not OK' (truthy), so the assertion passes regardless of what functionUnderTest actually does.
This does not meaningfully test the function and is misleading.
Option C:
console.assert(functionUnderTest(true), 'OK');
functionUnderTest(true) returns a Promise, not the string 'OK' directly.
A Promise object is always truthy.
So console.assert(promise, 'OK') will pass, even if the promise later rejects.
Also, there is no await, so we are not actually waiting for the async result.
This is not a correct way to assert on an async function's resolved value.
Option D:
console.assert(await functionUnderTest(true), 'not OK');
await functionUnderTest(true) still resolves to 'OK' (truthy).
console.assert('OK', 'not OK'); passes.
However, the message 'not OK' is the opposite of what we expect for the success case and is only used when the condition fails.
This makes the assertion logically inconsistent with the function behavior (it would show "not OK" if the assertion failed).
Therefore, the only assertion that:
Properly waits on the async function, and
Has expectation text that matches the successful behavior ('OK')
is:
Answe r: A
Study Guide / Concept Reference (no links):
async and await behavior in JavaScript
Promises resolving vs rejecting in async functions
console.assert(condition, message) usage
Truthy and falsy values in JavaScript
Comma operator (a, b) semantics
NEW QUESTION # 92
......
You will also improve your time management abilities by using JS-Dev-101 Practice Test software. You will not face any problems in the final JS-Dev-101 exam. This is very important for your career. And this GetValidTest offers 365 days updates. The price is affordable. You can download it conveniently
JS-Dev-101 Exam Cram: https://www.getvalidtest.com/JS-Dev-101-exam.html
BTW, DOWNLOAD part of GetValidTest JS-Dev-101 dumps from Cloud Storage: https://drive.google.com/open?id=1AsP_YQaWdrC66hgpZcDWGKBtTLoDLhGN