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| Section | Weight | Objectives |
|---|---|---|
| Objects, Functions, and Classes | 25% | - Modules and imports/exports - Closures and execution context - Object creation, properties, and methods - Decorators and advanced function patterns - Function definitions, parameters, and scope - Class syntax, inheritance, and prototypes |
| Server-Side JavaScript | 8% | - Core Node.js modules - Module system and require/import - Node.js fundamentals and runtime - Command-line tools and scripts |
| Browsers and Events | 17% | - Browser APIs and Web Storage - Script loading and execution order - Document Object Model (DOM) manipulation - Event handling, propagation, and delegation - Window and document object properties |
| Asynchronous Programming | 13% | - Async/await syntax - Event loop and micro/macro tasks - Fetch API and HTTP requests - Callbacks and callback hell - Promises and chaining |
| Variables, Types, and Collections | 23% | - JSON parsing and usage - Truthy and falsy values - Array methods and data manipulation - Working with strings, numbers, dates, and booleans - Variable declaration and initialization - Type coercion and conversion rules |
| Testing | 7% | - Code coverage and best practices - Unit testing concepts - Testing frameworks and assertions - Test doubles and mocks |
| Debugging and Error Handling | 7% | - Error types and exception handling - Debugging tools and breakpoints - Console methods and logging - Defensive programming practices |
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NEW QUESTION # 126
A developer removes the HTML class attribute from the checkout button, so now it is simply:
< button > Checkout < /button >
There is a test to verify the existence of the checkout button, however it looks for a button with class= " blue "
. The test fails because no such button is found.
Which type of test category describes this test?
Answer: A
Explanation:
Definitions in testing context (treating "positive" as "test reports a bug/failure"):
* True positive : System has a bug; test correctly fails.
* False positive : System is correct; test fails (reports a bug that isn't actually a bug).
* True negative : System has a bug; test correctly passes indicating "no success" in detection context (less common phrasing here).
* False negative : System has a bug; test incorrectly passes (missed bug).
Here:
* The real requirement , as stated, is to verify the existence of the checkout button .
* The button still exists ( < button > Checkout < /button > ), so the system behavior is correct regarding that requirement.
* The test, however, is checking for an overly specific condition (class= " blue " ), which is not actually part of the stated requirement.
* The test fails , saying there is a problem (no button with class= " blue " ), even though from the requirement standpoint, the checkout button is present.
So:
* No real bug concerning presence of checkout button.
* Test reports a failure # a false positive .
Therefore, the correct category is D, False positive.
NEW QUESTION # 127
Refer to the code below:
flag();
function flag() {
console.log( ' flag ' );
}
const anotherFlag = () = > {
console.log( ' another flag ' );
}
anotherFlag();
What is result of the code block?
Answer: D
Explanation:
Key points:
* Function declarations are hoisted (their definitions are available before the line where they appear).
* Function expressions assigned to const or let are not hoisted as callable functions, but here anotherFlag is only used after it is defined.
Step-by-step:
* flag(); at the top:
* flag is a function declaration defined later; due to hoisting, it is available.
* It logs ' flag ' .
* The declaration:
function flag() {
console.log( ' flag ' );
}
is already in effect (hoisted before execution).
* const anotherFlag = () = > { console.log( ' another flag ' ); } defines anotherFlag as an arrow function.
* anotherFlag(); is called after its definition; this is valid and logs ' another flag ' .
No errors occur. The console output is:
* flag
* another flag
So option D is correct.
Concepts: function hoisting, difference between function declarations and function expressions, execution order.
NEW QUESTION # 128
A class was written to represent regular items and sale items. Code:
01 let regItem = new Item( ' Scarf ' , 55);
02 let saleItem = new SaleItem( ' Shirt ' , 80, .1);
03 Item.prototype.description = function() { return ' This is a ' + this.name; }
04 console.log(regItem.description());
05 console.log(saleItem.description());
06
07 SaleItem.prototype.description = function() { return ' This is a discounted ' + this.name; }
08 console.log(regItem.description());
09 console.log(saleItem.description());
What is the output?
Answer: A
Explanation:
* At line 03, the developer assigns:
Item.prototype.description = function() { return ' This is a ' + this.name; } This affects all objects whose prototype chain includes Item.prototype .
* regItem inherits from Item # gets this method.
* saleItem, as an instance of SaleItem, also inherits Item.prototype (since SaleItem uses prototype inheritance from Item), so it also has this method at this moment.
Outputs at lines 04 and 05:
* regItem.description() # " This is a Scarf "
* saleItem.description() # " This is a Shirt "
* At line 07, the developer overrides the method on SaleItem.prototype :
SaleItem.prototype.description = function() {
return ' This is a discounted ' + this.name;
}
From this point:
* regItem still uses the Item.prototype version
* saleItem uses the overridden SaleItem.prototype version
Outputs at lines 08 and 09:
* regItem.description() # " This is a Scarf "
* saleItem.description() # " This is a discounted Shirt "
Combining all results:
This is a Scarf
This is a Shirt
This is a Scarf
This is a discounted Shirt
This matches option B .
JavaScript Knowledge References (text-only)
* Objects created from constructor functions use prototype chaining.
* Overriding a subclass prototype method does not affect the parent class prototype.
* Instances inherit the most specific version of the method on their prototype chain.
NEW QUESTION # 129
A developer creates a generic function to log custom messages in the console. To do this, the function below is implemented.
01 function logStatus(status){
02 console./*Answer goes here*/{'Item status is: %s', status};
03 }
Which three console logging methods allow the use of string substitution in line 02?
Answer: A,C
NEW QUESTION # 130
Refer to the code below:
01 const exec = (item, delay) =>{
02newPromise(resolve => setTimeout( () => resolve(item), delay)),
03 async function runParallel() {
04 Const (result1, result2, result3) = await Promise.all{
05 [exec ('x', '100') , exec('y', 500), exec('z', '100')]
06 );
07 return `parallel is done: $(result1)$(result2)$(result3)`;
08 }
}
}
Which two statements correctly execute the runParallel () function?
Choose 2 answers
Answer: B,D
NEW QUESTION # 131
......
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