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| Section | Weight | Objectives |
|---|---|---|
| Topic 1: Asynchronous Programming | 13% | - Callbacks - Async/Await syntax - Promises (creation, chaining, error handling) - Asynchronous patterns for business requirements - Event loop and execution flow |
| Topic 2: Debugging and Error Handling | 7% | - Console methods for debugging - Breakpoints and code inspection - Custom error types - Error handling techniques (try/catch/finally) |
| Topic 3: Server Side JavaScript | 8% | - CLI commands - Node.js fundamentals - Core Node.js modules - Server-side JavaScript implementations - Package management (npm) |
| Topic 4: Variables, Types, and Collections | 23% | - Primitive and complex data types - Truthy and falsy evaluations - Arrays and collections - Variable declarations and initialization - JSON parsing and manipulation - Type coercion and conversion - Strings, numbers, and dates |
| Topic 5: Objects, Functions, and Classes | 25% | - Execution flow and context - Function declarations and expressions - Variable scope and closures - Arrow functions - ES6 classes and inheritance - Higher-order functions - Prototypal inheritance - Modules and decorators - Object creation and manipulation |
| Topic 6: Browser and Events | 17% | - Interacting with forms and user input - Event handling and listeners - Browser Developer Tools usage - DOM manipulation - Browser-specific APIs - Event propagation (bubbling and capturing) |
| Topic 7: Testing | 7% | - Writing and modifying unit tests - Test effectiveness evaluation - Unit testing concepts - Test coverage and reliability |
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NEW QUESTION # 137
Refer to the code:
01 const event = new CustomEvent(
02 // Missing code
03 );
04 obj.dispatchEvent(event);
A developer needs to dispatch a custom event called update to send information about recordId.
Which two options can be inserted at line 02?
Answer: A,C
Explanation:
The correct constructor signature for CustomEvent is:
new CustomEvent(eventName, optionsObject)
Where:
* eventName is a string.
* optionsObject may include:
* detail # used to pass custom data
* bubbles
* cancelable, etc.
Example:
new CustomEvent( ' update ' , {
detail: { recordId: ' 123abc ' }
});
Now evaluate each option:
Option A
{ type: ' update ' , recordId: ' 123abc ' }
Incorrect: The constructor requires (eventName, options), not a single object. type is not used this way.
Option B
' update ' , { detail: { recordId: ' 123abc ' } }
Correct format. detail is the proper place for custom event data.
Option C
' update ' , ' 123abc '
Incorrect: The second argument must be an object (options), not a string.
Option D
' update ' , { recordId: ' 123abc ' }
Acceptable because any extra properties on the options object are still allowed, even though best practice is to use detail.
This still creates a valid CustomEvent, and the event will dispatch successfully.
Thus the two correct answers are B and D .
JavaScript Knowledge References (text-only)
* new CustomEvent(name, options) is the required syntax.
* The detail property of the options object is the standard location for custom data.
* The second argument must be an object; other types are invalid.
NEW QUESTION # 138
Which three browser specific APIs are available for developers to persist data between page loads ?
Choose 3 answers
Answer: A,B,C
NEW QUESTION # 139
Refer to the code below:
01 x = 3.14;
02
03 function myFunction() {
04 ' use strict ' ;
05 y = x;
06 }
07
08 z = x;
09 myFunction();
Considering the implications of ' use strict ' on line 04, which three statements describe the execution of the code?
Answer: A,B,C
Explanation:
* Behavior of non-strict global code The script does not begin with a ' use strict ' directive at the top level, so the global code (outside any function) runs in non-strict (sloppy) mode.
* Line 01: x = 3.14; In non-strict mode, assigning to an undeclared identifier (no var, let, or const) creates an implicit global variable. So after line 01, x exists and equals 3.14.
* Line 08: z = x; This also runs in non-strict mode. Since x is already defined (from line 01), z is set to
3.14. Therefore, statement B is correct: z is equal to 3.14.
* Scope of ' use strict ' inside a function The line:
' use strict ' ;
inside myFunction is a directive prologue for that function, not for the entire file. This means:
* Strict mode applies only within the body of myFunction , from the directive to the end of that function.
* It does not retroactively affect code before the function or code outside of it.
Therefore:
* Statement A is incorrect: ' use strict ' is not "hoisted" to affect the whole file. It only affects the function body.
* Statement C is incorrect: strict mode does not apply from line 04 to the end of the file; it only applies within myFunction, not to global lines like 01, 08, or 09.
* Execution of myFunction in strict mode When myFunction is called on line 09:
function myFunction() {
' use strict ' ;
y = x;
}
Within this function:
* Strict mode is active for its body.
* In strict mode, assigning to an undeclared variable (like y here) is not allowed and results in a ReferenceError at runtime.
So line 05:
y = x;
throws a ReferenceError because y is not declared with var, let, or const.
Therefore, statement E is correct: line 05 throws an error.
* Why statement D is considered correct Statement D says: ' use strict ' has an effect only on line 05.
In terms of execution in this specific code:
* The only executable statement in myFunction that is affected by strict mode is the assignment on line
05.
* The directive itself on line 04 is not a "normal" runtime operation; it is a directive that sets the mode.
* There are no other statements inside the function that behave differently under strict mode; only the line that assigns to the undeclared variable shows a strict-mode effect.
So, describing the practical execution behavior of this snippet, strict mode manifests its effect only on line 05, making statement D correct in this context.
Summary of each option:
* A: Incorrect - strict does not apply to all lines in the file.
* B: Correct - z becomes 3.14 in non-strict global code.
* C: Incorrect - strict does not affect code outside the function.
* D: Correct - in this code, the only behavioral effect of strict mode is on line 05.
* E: Correct - line 05 throws a ReferenceError due to assignment to undeclared y under strict mode.
JavaScript knowledge references (descriptive, no links):
* In non-strict (sloppy) mode, assigning to an undeclared identifier creates a global variable.
* ' use strict ' inside a function body enables strict mode for that function only.
* In strict mode, assigning to an undeclared variable results in a ReferenceError.
* Directive prologues ( ' use strict ' ) affect only their containing function or script, not other scopes.
NEW QUESTION # 140
Considering type coercion, What does the following expression evaluate to?
True + '13 ' + NaN
Answer: A
NEW QUESTION # 141
Refer to the code below:
Which code executes syhello once, two minutes from now?
Answer: B
NEW QUESTION # 142
......
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