ISA Lecture Week 5: Asynchronous JavaScript
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Questions and Answers

What status code indicates a successful response from a server?

  • 500
  • 400
  • 404
  • 200 (correct)

    • A status code of 500 indicates that the requested resource does not exist.

    False (B)

    What does the acronym API stand for?

    Application Programming Interface

    What does asynchronous JavaScript allow you to perform without blocking the main thread?

    <p>Long network requests (C)</p> Signup and view all the answers

    The _____ API can return the coordinates of the user's location.

    <p>Geolocation</p> Signup and view all the answers

    Match the following APIs with their descriptions:

    <p>YouTube API = Allows you to display videos on a web site Twitter API = Allows you to display Tweets on a web site Facebook API = Allows you to display Facebook info on a web site Geolocation API = Returns the coordinates of the user's location</p> Signup and view all the answers

    What is the purpose of a callback function?

    <p>To execute a function after another function completes (B)</p> Signup and view all the answers

    A callback function is a function that cannot be passed as an argument to another function.

    <p>False (B)</p> Signup and view all the answers

    What does a promise in JavaScript represent?

    <p>An object that holds the result of an asynchronous operation (B)</p> Signup and view all the answers

    A callback function can only be an anonymous function.

    <p>False (B)</p> Signup and view all the answers

    Which of the following is an example of a Browser API?

    <p>Geolocation API (C)</p> Signup and view all the answers

    What is the main disadvantage of using single-threaded programming in JavaScript?

    <p>It does not allow for simultaneous operations, which can lead to blocking.</p> Signup and view all the answers

    The ______ function is used in JavaScript to execute code after a specified delay.

    <p>setTimeout</p> Signup and view all the answers

    JSON is a text format that is syntactically identical to JavaScript object notation.

    <p>True (A)</p> Signup and view all the answers

    The fetch() method can only make GET requests.

    <p>False (B)</p> Signup and view all the answers

    What term describes the situation where multiple nested callbacks make code difficult to read?

    <p>Callback Hell</p> Signup and view all the answers

    A callback function allows JavaScript to know when an __________ operation has a result.

    <p>asynchronous</p> Signup and view all the answers

    Match the following concepts with their descriptions:

    <p>Callback functions = Functions passed as arguments to be called later Promises = Objects that represent the eventual completion of an asynchronous operation AJAX = Asynchronous JavaScript and XML async-await = Syntactic sugar to simplify working with Promises</p> Signup and view all the answers

    What is JSON commonly used for?

    <p>Storing and transporting data</p> Signup and view all the answers

    What are the two main methods provided by a promise for handling results?

    <p>then() and catch()</p> Signup and view all the answers

    Match the following terms related to callback functions:

    <p>Greet = Logs a greeting message and calls a callback SayGoodbye = A function that can be passed as a callback AsyncOperation = Stimulates an asynchronous task Print = Function executed within a callback</p> Signup and view all the answers

    The fetch method returns a special JavaScript object called a ______.

    <p>promise</p> Signup and view all the answers

    What term describes the situation where you have multiple nested callback functions?

    <p>Callback hell (D)</p> Signup and view all the answers

    AJAX stands for Asynchronous JavaScript and XML.

    <p>True (A)</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>then() = Method for handling successful responses catch() = Method for handling errors in promises fetch() = Method for making HTTP requests Response object = Object containing the data returned from an API call</p> Signup and view all the answers

    Which of the following best describes Callback Hell?

    <p>A situation where callbacks are nested and code becomes unreadable (D)</p> Signup and view all the answers

    What type of JavaScript calls are facilitated by using asynchronous programming?

    <p>Network calls or long-running operations.</p> Signup and view all the answers

    Which of the following issues do promises help to avoid?

    <p>Callback hell (A)</p> Signup and view all the answers

    The result of an asynchronous operation can either be data or an error.

    <p>True (A)</p> Signup and view all the answers

    Variables used to store the Response object can only be named 'response'.

    <p>False (B)</p> Signup and view all the answers

    What method is used in the asyncOperation function to simulate an asynchronous task?

    <p>setTimeout</p> Signup and view all the answers

    An HTTP ______ code communicates the server's response to a browser's request.

    <p>status</p> Signup and view all the answers

    Which of the following are valid data types that can be included in JSON?

    <p>Booleans (A), Objects (C), Strings (D)</p> Signup and view all the answers

    JSON data must be written using single quotes for the keys.

    <p>False (B)</p> Signup and view all the answers

    What is the function used in JavaScript to convert a JSON string into a JavaScript object?

    <p>JSON.parse()</p> Signup and view all the answers

    JSON values can be included in an array, which is written inside [______].

    <p>]</p> Signup and view all the answers

    Match the following JSON constructs with their descriptions:

    <p>JSON Object = Written inside curly braces JSON Array = Written inside square brackets JSON Key/Value Pair = Consists of a key followed by a colon and value JSON Syntax = Data is in name/value pairs separated by commas</p> Signup and view all the answers

    Which of the following is true about JSON?

    <p>JSON is text only and can be used across different programming languages. (D)</p> Signup and view all the answers

    JSON permits the use of nested objects within arrays.

    <p>True (A)</p> Signup and view all the answers

    Give an example of a JSON object containing the key 'age' with a numeric value.

    <p>{ &quot;age&quot;: 22 }</p> Signup and view all the answers

    Study Notes

    ISA Lecture Week 5: Asynchronous JavaScript and APIs

    • Previous week topics covered: Arrow Functions, Anonymous Functions, IIFEs (Immediately Invoked Function Expressions), Higher-Order Functions, Map, Reduce, Filter, Foreach Iteration, HTML DOM, Virtual DOM, JavaScript Selectors, JavaScript Events and event handlers

    • This week's agenda: Understanding Asynchronous Scripting, Callback functions and Callback Hell, JavaScript Promises, Fetch Method, Axios

    • Asynchronous JavaScript: JavaScript is single-threaded, meaning only one task can happen at a time. This can block the main thread if long operations (like network requests) are performed. Asynchronous JavaScript methods (AJAX, Callback, Promises, async-await) allow for operations to occur without blocking the main thread. One example is the window.alert() function.

    • Synchronous vs. Asynchronous example: A synchronous example in JavaScript shows statements executing sequentially. An asynchronous example using setTimeout shows how tasks can run concurrently without blocking the main thread. Statements after setTimeout are executed immediately, and the setTimeout callback is executed after the delay.

    • Callback Functions: A callback function is a function passed as an argument to another function, to be executed later. Useful for handling events or actions after another operation is complete. Can avoid blocking the main thread.

    • Callback Hell: Nested callbacks can create complex and hard-to-read code. This is a common issue with multiple asynchronous operations, making debugging and maintenance challenging.

    • JavaScript Promises: A promise is an object representing the eventual result of an asynchronous operation. A promise can either be fulfilled (resolved) or rejected. Promises provide a structured way to handle async operations, avoiding callback hell. Key promise methods are then(), for successful actions and catch(), for handling errors.

    • Fetch Method: A promise-based API for fetching resources (e.g., from a server). fetch() is an HTTP request that returns a promise. You can use .then() to handle the response (and .catch() for errors). The response can be parsed to JSON to get the data.

    • Web APIs: An API (Application Programming Interface) is a set of functions and procedures allowing software systems to interact. Web APIs can act as intermediaries for interactions between applications or a server to a front-end. Web APIs can be built into the browser or external.

    • Third-party APIs: APIs not built into a browser. Examples include YouTube API, Twitter API, and Facebook API, which you have to call to get the specific data.

    • JSON (JavaScript Object Notation): A text-based format for storing and transporting data. JSON objects are superficially similar to JavaScript objects.

    • Key differences between JSON and JavaScript objects: JSON keys must be enclosed in double quotes, whereas JavaScript objects don't always require quotes; JSON cannot contain functions; JSON can be used in different languages, not just JavaScript.

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    ISA Lecture Week 5 - Asynchronous JavaScript and API PDF

    Description

    In this quiz, explore the concepts introduced in Week 5 of the ISA lecture series focusing on Asynchronous JavaScript and APIs. Topics include Callback functions, JavaScript Promises, and the Fetch method. Test your knowledge on how these concepts help manage execution without blocking the main thread.

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