Why might recursive function expressions cause issues in certain scenarios?
- They can cause an infinite loop and lead to a stack overflow error.
- They can only be used for mathematical calculations and not for general-purpose recursion.
- They can't access variables from the outer scope.
- They are less efficient than iterative approaches.
Recursive function expressions, if not designed carefully, can cause infinite recursion, which leads to a stack overflow error. Each recursive call adds a new function call to the stack, and if there's no base case to stop the recursion, it will continue indefinitely. It's essential to have a termination condition to prevent such issues.
In which context does the "this" keyword not refer to the object that calls the function?
- Global context
- Method context
- Function context
- Constructor context
The "this" keyword in JavaScript does not refer to the object that calls the function in the global context. In the global context, "this" points to the global object, which is usually the "window" object in browsers. This can be a source of confusion, so it's essential to understand the various contexts in which "this" behaves differently.
What is a closure in JavaScript?
- A secure way to store passwords
- A private function
- A way to handle exceptions
- A function that remembers its lexical scope
A closure in JavaScript is a function that "remembers" its lexical scope, even when it's executed outside that scope. This allows the function to maintain access to variables from its parent scope, creating a powerful mechanism for encapsulation and data privacy.
Which array method adds elements to the beginning of an array?
- push()
- unshift()
- concat()
- splice()
The unshift() method is used to add elements to the beginning of an array. It's particularly useful when you want to insert one or more elements at the start of an existing array without affecting the order of the existing elements. Unlike push(), which adds elements to the end, unshift() works at the beginning.
You're developing a Node.js application and notice that the "this" keyword inside a regular function, defined in the global scope, refers to something different than you're used to in client-side JavaScript. What does "this" refer to in this context?
- It refers to the Node.js global object (e.g., "global" or "window")
- It refers to the "exports" object
- It refers to the "module.exports" object
- It refers to the function itself
In Node.js, when you define a regular function in the global scope (outside any function or module), "this" inside that function refers to the Node.js global object (e.g., "global" in Node.js or "window" in the browser). This behavior is different from client-side JavaScript, where "this" in the global scope refers to the global window object.
In JavaScript, the ________ function is often used for delaying the execution of a function in an asynchronous manner.
- setTimeout
- setInterval
- asyncWait
- delayFunction
In JavaScript, the setTimeout function is often used for delaying the execution of a function in an asynchronous manner. It schedules the execution of a function after a specified time delay, allowing for tasks like animations or asynchronous operations to be handled.
Can a function expression be used before it is defined in the code?
- No, function expressions can only be used after their definition.
- Yes, function expressions are hoisted and can be used before they are defined.
- It depends on whether the function expression is named or anonymous.
- No, function expressions are not valid in JavaScript.
Function expressions are not hoisted in JavaScript, which means they can only be used after they are defined in the code. Attempting to use a function expression before its declaration will result in an error. This is different from function declarations, which are hoisted and can be used before their declaration. It's essential to understand this behavior to avoid bugs and unexpected behavior in your JavaScript programs.
Arrow functions were introduced in ECMAScript _________.
- 5
- 6
- 2015
- 2018
Arrow functions were introduced in ECMAScript 2015 (ES6). ES6 brought many enhancements to JavaScript, and arrow functions were one of the notable additions. They offer a more concise syntax for defining functions and have lexical scoping for this, making them a valuable addition to modern JavaScript.
In a while loop, placing a ________ statement inside the loop can help prevent infinite loops by providing an explicit exit.
- Break
- Continue
- Return
- Stop
In a while loop, placing a "break" statement inside the loop can help prevent infinite loops by providing an explicit exit condition. When a certain condition is met, the "break" statement terminates the loop, allowing you to exit the loop when necessary and avoid infinite iterations.
What is the most common issue developers might face when working with closures and loops together?
- Variable hoisting
- Memory leaks
- Unexpected type coercion
- Event propagation
The most common issue when working with closures and loops together is the creation of memory leaks. This happens when closures inside loops capture references to variables that are continuously changing in the loop, preventing them from being garbage collected, and leading to increased memory consumption. It's crucial to understand and manage these cases to avoid performance problems.