What is the primary purpose of Jest in JavaScript?
Unit testing JavaScript code
What does the following code in Jest do?
JavaScript
const mockFn = jest.fn();
mockFn('test');
console.log(mockFn.mock.calls[0][0]);
Returns the number of function calls
Logs all arguments passed to the mock function
Logs the first argument of the first call
What is the purpose of JavaScript's garbage collector?
Frees memory of unused variables
Automatically removes unreferenced objects to free memory
What is the most common algorithm used in JavaScript garbage collection?
What is lazy loading in web development?
Preloading all resources at once
Caching resources for later use
Loading resources in parallel
Delaying the loading of resources until needed
Which attribute enables lazy loading of images in HTML?
What is the main purpose of debouncing in JavaScript?
To limit function calls to a fixed rate
To delay a function call until a pause in events
To cache function results
What is throttling in JavaScript?
Combining multiple function calls into one
Delaying function calls until events stop
Ensuring a function is called at most once in a specified time period
What is the key difference between debouncing and throttling?
Throttling is faster than debouncing.
Debouncing is used for lazy loading, while throttling is for memory management.
Debouncing waits for a pause in events, while throttling ensures periodic execution.
Both are identical and interchangeable.
What does the following Jest test case do?
JavaScript
test('adds 1 + 2 to equal 3', () => {
expect(1 + 2).toBe(3);
});
Logs the result of the addition
Throws an error if the result is not 3
Mocks the addition function
Asserts that the sum of 1 and 2 equals 3
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