How do you denote a block of code to be executed if a condition is true?
- By enclosing it in curly braces {}
- By using square brackets []
- By using parentheses ()
- By using angle brackets <>
In JavaScript, you denote a block of code to be executed if a condition is true by enclosing it in curly braces {}. These braces create a code block that allows you to execute multiple statements when the condition is met.
The _______ method is used to handle errors in Promises.
- .then()
- .catch()
- .resolve()
- .reject()
The correct method to handle errors in Promises is the .catch() method. When a Promise is rejected, the .catch() method is called with the reason for the rejection, allowing you to handle and manage errors in your asynchronous code effectively.
JavaScript was introduced to the world in the year _________.
- 1995
- 2000
- 1998
- 1993
JavaScript was introduced to the world in the year 1995. It was first released by Netscape as part of their Navigator 2.0 web browser. JavaScript quickly gained popularity as a client-side scripting language for web development.
What is a potential downside of using async/await syntax?
- It makes code harder to read and understand.
- It can't be used with Promises.
- It always leads to callback hell.
- It reduces code efficiency.
One potential downside of using async/await is that it can make code harder to read and understand, especially for developers who are not familiar with asynchronous programming. It may lead to nested code blocks, which can be challenging to follow. However, when used correctly, async/await can make asynchronous code more readable.
Which organization developed JavaScript?
- Microsoft
- Mozilla
- Netscape
- Oracle
JavaScript was developed by Netscape. Brendan Eich created it in 10 days in September 1995. While Netscape is best known for its role in the development of JavaScript, it didn't create other popular languages like Java.
To prevent variables from being added to the global object, it is common to use a(n) _______ function expression.
- IIFE (Immediately Invoked Function Expression)
- Arrow
- Anonymous
- Prototype
To prevent variables from polluting the global object, an IIFE (Immediately Invoked Function Expression) is commonly used. It encapsulates code within a function scope and immediately executes it, keeping variables private and not accessible from the global scope.
The method _______ can be used to add new elements to the end of an array.
- push()
- unshift()
- add()
- append()
The push() method in JavaScript can be used to add new elements to the end of an array. This method modifies the original array and is commonly used when you want to add elements to the end of an array, expanding its length. For example, myArray.push('newElement') would add 'newElement' to the end of myArray.
What value types can be used for case comparisons in a switch statement?
- Strings, numbers, and symbols
- Arrays, objects, and booleans
- Only numbers and booleans
- Functions and undefined values
In a switch statement, you can use strings, numbers, and symbols as values for case comparisons. These values are compared strictly, meaning both value and type must match for the associated code block to execute.
You are working on a form validation feature where you want to select all input elements within a form. Which method allows you to select all input elements within a specific form element?
- querySelectorAll('input')
- getElementById('form')
- getElementsByTag('form')
- querySelectorAll('form input')
To select all input elements within a specific form, you should use the querySelectorAll('form input') method. This allows you to target input elements that are descendants of a specific form element. The other options are incorrect because they either select all input elements on the page or attempt to select a form element by ID or tag name, which doesn't filter the input elements within it.
Which of the following patterns is NOT facilitated by using closures in JavaScript?
- Singleton Pattern
- Module Pattern
- Factory Pattern
- Observer Pattern
Closures in JavaScript facilitate patterns like the Singleton Pattern, Module Pattern, and Observer Pattern. These patterns use closures to encapsulate data and create private scopes. However, the Factory Pattern is not primarily facilitated by closures. The Factory Pattern focuses on creating and returning objects or instances, which can be achieved without closures. It relies more on object creation and instantiation rather than scope encapsulation.