How can debugging be enabled in an Express application for development purposes?
- Set app.debug = true;
- Use the DEBUG environment variable
- Add console.debug statements
- Call app.enable('debug');
Debugging can be enabled in an Express application for development purposes by using the DEBUG environment variable. This allows you to selectively enable debugging for specific modules or components. The other options do not enable debugging in the standard way for Express applications.
In a distributed caching system, how is cache coherence typically maintained?
- Using a consistency protocol like "invalidation"
- By periodically clearing the cache
- Through manual intervention by administrators
- Automatically with a "write-through" strategy
Cache coherence in a distributed caching system is typically maintained using a consistency protocol like "invalidation." This protocol ensures that cached data is invalidated or updated when changes occur, ensuring data consistency across distributed nodes.
How can you secure sensitive information like API keys in your Express application?
- Store API keys in plain text within your code
- Use environment variables to store API keys
- Embed API keys in the URL parameters
- Include API keys in the client-side JavaScript
To secure sensitive information like API keys in an Express application, it is essential to use environment variables. Storing API keys in plain text within your code is not secure, embedding them in URL parameters can expose them, and including them in client-side JavaScript makes them accessible to anyone inspecting the client code.
Which method in Express is used to handle HTTP GET requests to a specified route?
- app.post()
- app.get()
- app.route()
- app.put()
In Express, the app.get() method is used to handle HTTP GET requests to a specified route. This method is a part of the Express application instance (app) and is used to define routes that respond to HTTP GET requests. The other options (app.post(), app.route(), and app.put()) are used for handling other HTTP methods (POST, routing, and PUT) respectively.
______ caching involves storing cache data in the client's browser to reduce server load and increase load speed.
- Server-side
- Client-side
- In-memory
- Distributed
Client-side caching involves storing cache data in the client's browser to reduce server load and increase load speed. This can be achieved using techniques like browser caching and local storage.
Which of the following is used to perform a conditional (ternary) operation in JavaScript?
- if-else
- switch
- ?:
- for
The ?: operator is known as the ternary operator in JavaScript and is used for conditional operations. It allows you to perform a quick inline conditional check and return one of two values based on the condition. The other options (if-else, switch, for) are not used for conditional operations in the same way.
You are developing a feature to filter out invalid user inputs. Which conditional structures can be used to validate multiple conditions effectively and execute specific code blocks?
- if...else if...else statements
- switch statement
- try...catch statements
- while loop
To validate multiple conditions effectively and execute specific code blocks for filtering out invalid user inputs, you would typically use if...else if...else statements. These conditional structures allow you to check various conditions and perform different actions based on the outcome. The switch statement is more suitable for situations with a single value and multiple cases, and try...catch is primarily used for error handling. A while loop is not a conditional structure for validation but a looping mechanism.
When installing packages using npm, where are the dependencies listed?
- In the "package.json" file under the "dependencies" section
- In the "node_modules" directory
- In the project's main JavaScript file
- In a separate "dependencies.json" file
When you install packages using npm, the dependencies are listed in the "package.json" file under the "dependencies" section. This file acts as a manifest for your project and keeps track of its dependencies.
In Jest, ______ is used to generate snapshot files of a component's output render.
- snapshot
- renderSnapshot
- createSnapshot
- toMatchSnapshot
In Jest, the toMatchSnapshot function is used to generate snapshot files of a component's output render. This allows you to capture the expected output and compare it to the actual output during subsequent test runs. The other options do not represent the correct Jest function for this purpose.
What is the scope of a variable declared using the var keyword inside a function?
- Global scope
- Function scope
- Block scope
- Local scope
In JavaScript, a variable declared using the var keyword inside a function has function scope. This means it is accessible within the entire function but not outside of it. Unlike let and const, var does not have block scope.