The ________ operator can be used to compare both value and type in JavaScript.
- Equality (===)
- Assignment (=)
- Identity (==)
- Inequality (!=)
The Equality (===) operator can be used to compare both value and type in JavaScript. It checks if two values are strictly equal, meaning they have the same value and the same data type. The other options, such as Assignment (=) and Identity (==), do not perform strict value and type comparison. Inequality (!=) checks for inequality.
The process of an object inheriting properties and behaviors (methods) from its prototype is known as _________.
- Encapsulation
- Inheritance
- Polymorphism
- Abstraction
Inheritance is the process by which an object inherits properties and behaviors (methods) from its prototype or parent object. JavaScript uses a prototype-based inheritance model, where objects inherit from other objects, and this is a fundamental concept in the language.
The ________ method is used to read a Response stream and return it as a blob.
- text()
- json()
- blob()
- arrayBuffer()
The blob() method is used to read a Response stream and return it as a blob object. This is commonly used when dealing with binary data or files. The other options (text(), json(), arrayBuffer()) are used for different types of Response data processing.
You are debugging a web application and notice that a "for" loop is causing the webpage to hang. What could be a potential reason and how might you solve it?
- Infinite Loop
- Excessive DOM Manipulation
- Missing Loop Condition
- Insufficient Memory Allocation
One potential reason for a webpage hang caused by a "for" loop is excessive DOM manipulation within the loop, which can block the main thread. To solve this, consider moving DOM manipulation outside the loop or optimizing the DOM operations. An infinite loop, missing loop condition, or insufficient memory allocation could also cause hangs but are less likely in this context. JavaScript Debugging
What is lexical scoping in JavaScript?
- A type of error handling in JavaScript
- A scoping mechanism in JavaScript
- A method to declare global variables
- A JavaScript data type
Lexical scoping in JavaScript refers to the way variable scope is determined by the placement of variables in the source code. Variables declared inside a function are accessible within that function, creating a hierarchy of scope. This helps prevent variable conflicts and promotes clean code.
If an array arr has a length n, executing arr.push(x) will set arr[_______] equal to x.
- arr.length - 1
- arr.length + 1
- arr.length
- arr.length - 2
When you use arr.push(x), it appends the element x to the end of the array and increases the length property of the array by 1. Therefore, the new element will be at the index arr.length - 1, which is one less than the new length. For example, if arr has a length of 5, arr.push(x) will add x at index 4.
Which property of the Response object represents the status text of the response?
- statusText
- statusCode
- status
- statusDescription
The statusText property of the Response object represents the status text of the HTTP response. It provides a textual description of the HTTP status code, such as "OK" for status code 200 or "Not Found" for status code 404. This property is useful for understanding the meaning of the response status code in a more human-readable form.
You are debugging a JavaScript application and encounter a ReferenceError at runtime, despite a function being defined in the code. What could be the possible reason if the function was defined using a function expression?
- The function is declared within a block scope.
- The function was defined in strict mode.
- The function was hoisted to the top of the code.
- The function was defined inside another function.
When a function is defined using a function expression and declared within a block scope, it may not be accessible outside of that block, resulting in a ReferenceError. This is because the function's scope is limited to the block where it's defined.
When dealing with callbacks, the first argument is traditionally
- Callback
- Error
- Function
- Result
When dealing with callbacks, the first argument is traditionally reserved for Error. This convention allows developers to handle errors gracefully when executing asynchronous operations. It helps in proper error handling and prevents unexpected crashes in your code.
How does the browser determine the path along which the event propagates?
- Bubbling phase and capturing phase both follow the DOM hierarchy from the target element to the document root.
- It is determined by the order in which event listeners were added.
- The browser chooses a random path for event propagation.
- It follows the DOM hierarchy from the document root to the target element.
The browser determines the path of event propagation based on the DOM hierarchy. Events can propagate in two phases: capturing and bubbling. In the capturing phase, events travel from the document root to the target element. In the bubbling phase, events travel from the target element back up to the document root. This order ensures that ancestors and descendants of the target element have an opportunity to handle the event.