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| Section | Weight | Objectives |
|---|---|---|
| Debugging and Error Handling | 7% | - Breakpoints and code inspection - Error handling techniques (try/catch/finally) - Custom error types - Console methods for debugging |
| Objects, Functions, and Classes | 25% | - Variable scope and closures - Prototypal inheritance - Modules and decorators - Object creation and manipulation - Execution flow and context - Function declarations and expressions - Arrow functions - Higher-order functions - ES6 classes and inheritance |
| Variables, Types, and Collections | 23% | - Variable declarations and initialization - JSON parsing and manipulation - Truthy and falsy evaluations - Type coercion and conversion - Strings, numbers, and dates - Primitive and complex data types - Arrays and collections |
| Testing | 7% | - Test effectiveness evaluation - Writing and modifying unit tests - Unit testing concepts - Test coverage and reliability |
| Server Side JavaScript | 8% | - Server-side JavaScript implementations - Package management (npm) - CLI commands - Core Node.js modules - Node.js fundamentals |
| Asynchronous Programming | 13% | - Async/Await syntax - Callbacks - Event loop and execution flow - Asynchronous patterns for business requirements - Promises (creation, chaining, error handling) |
| Browser and Events | 17% | - Browser-specific APIs - Browser Developer Tools usage - Event handling and listeners - Interacting with forms and user input - Event propagation (bubbling and capturing) - DOM manipulation |
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NEW QUESTION # 11
Which two console logs outputs NaN ?
Choose 2 answers
Answer: B,C
NEW QUESTION # 12
A developer receives a comment from the Tech lead that the code below gives an error.
Which line edit should be made to make this code run?
Answer: A
NEW QUESTION # 13
A Developer wrote the following code to test a sum3 function that takes in an array of
numbers and returns the sum of the first three number in the array, The test passes:
Let res = sum2([1, 2, 3 ]) ;
console.assert(res === 6 );
Res = sum3([ 1, 2, 3, 4]);
console.assert(res=== 6);
A different developer made changes to the behavior of sum3 to instead sum all of the numbers
present in the array. The test passes:
Which two results occur when running the test on the updated sum3 function ?
Choose 2 answers
Answer: A,C
NEW QUESTION # 14
A developer wants to create a simple image upload using the File API.
HTML:
< input type= " file " onchange= " previewFile() " >
< img src= " " height= " 200 " alt= " Image preview... " / >
JavaScript:
01 function previewFile() {
02 const preview = document.querySelector( ' img ' );
03 const file = document.querySelector( ' input[type=file] ' ).files[0];
04 // line 4 code
05 reader.addEventListener( " load " , () = > {
06 preview.src = reader.result;
07 }, false);
08 // line 8 code
09 }
Which code in lines 04 and 08 allows the selected local image to be displayed?
Answer: A
Explanation:
The File API in browsers provides the FileReader object to read file contents selected from < input type= " file " > .
Important knowledge points:
* new FileReader() creates a file-reading object.
* .readAsDataURL(file) reads a file and produces a Base64 URL string.
* The " load " event fires when the file has finished reading.
* reader.result contains the data URL after reading completes.
Therefore, the correct implementation must:
* Create a FileReader instance:
* const reader = new FileReader();
* Call:
* reader.readAsDataURL(file);
* Use the load event handler to assign the image preview:
* preview.src = reader.result;
Option B is the only option that matches valid JavaScript File API usage.
Option A is incorrect because File is not a constructor for reading files.
Option C is incorrect because URL.createObjectURL(file) must be assigned directly as a URL, not used with reader.result.
JavaScript Knowledge References (text-only)
* The file-reading interface in browsers is FileReader.
* readAsDataURL() loads files as Base64 data URLs.
* The load event indicates when the reader has finished and reader.result is available.
NEW QUESTION # 15
developer is trying to convince management that their team will benefit from using Node.js for a backend server that they are going to create. The server will be a web server that handles API requests from a website that the team has already built using HTML, CSS, and JavaScript.
Which three benefits of Node.js can the developer use to persuade their manager?
Choose 3 answers:
Answer: A,C,D
NEW QUESTION # 16
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