JavaScript Arrays and Functions Quiz

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Questions and Answers

In JavaScript, what is hoisting?

  • Treating a parameter as undefined if not passed a value in the arguments list
  • Moving all variable and function declarations to the top of the current scope (correct)
  • Accessing the arguments object to access the values passed to a function
  • Passing additional arguments to a function

What happens if there is a mismatch between the argument list and parameter list in JavaScript functions?

  • It gives an error
  • It automatically adjusts the parameter list to match the argument list
  • The parameter that is not passed a value is treated as undefined
  • The function still executes without any errors (correct)

What happens to variables and functions declared with let or const in JavaScript's hoisting behavior?

  • They are hoisted but not initialized
  • They are hoisted only if they are constants
  • They are hoisted to the top of the current scope
  • They are not hoisted (correct)

What is the purpose of the arguments object in JavaScript functions?

<p>To access additional arguments passed to the function (C)</p> Signup and view all the answers

What is the correct way to access values passed to a JavaScript function using an array?

<p>Using the args array (B)</p> Signup and view all the answers

What does JavaScript do with variables and function declarations by default?

<p>Hoist them to the top of the current scope (A)</p> Signup and view all the answers

In JavaScript, how are arrays created using the 'new Array' method?

<p>let arr = new Array(10, 20) (D)</p> Signup and view all the answers

What is the index of the last element in a JavaScript array of length n?

<p>n-1 (B)</p> Signup and view all the answers

How can you create a literal array in JavaScript?

<p>var alist = [1, 'ii', 'gamma', '4'] (D)</p> Signup and view all the answers

What happens when you modify the length property of a JavaScript array at runtime?

<p>The array length property affects the number of defined values in the array (A)</p> Signup and view all the answers

What is the correct syntax for defining a function in JavaScript?

<p>function function_name(parameter) (D)</p> Signup and view all the answers

What type of index does the 'for-in' loop in JavaScript return when used with an array?

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

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Study Notes

Hoisting in JavaScript

  • Hoisting is a behavior in JavaScript where variables and functions are moved to the top of their scope, regardless of their placement in the code.

Function Arguments and Parameters

  • A mismatch between the argument list and parameter list in JavaScript functions does not cause an error; instead, excess arguments are ignored, and excess parameters are set to undefined.

Let and Const in Hoisting

  • Variables and functions declared with let or const are not hoisted, unlike those declared with var; instead, they are placed in a "temporal dead zone" until they are declared.

The Arguments Object

  • The arguments object in JavaScript functions is an array-like object that contains the values passed to the function.

Accessing Function Arguments

  • To access values passed to a JavaScript function using an array, you can use the arguments object or the rest parameter syntax (...args).

Default Behavior

  • By default, JavaScript moves variables and function declarations to the top of their scope, but this can be overridden by using let or const.

Creating Arrays

  • Arrays can be created using the new Array method, but this is not recommended; instead, use the literal array syntax ([]).
  • Arrays can also be created using the literal array syntax, where each element is separated by a comma.

Array Index

  • The index of the last element in a JavaScript array of length n is n - 1.

Modifying Array Length

  • When you modify the length property of a JavaScript array at runtime, elements are added or removed from the end of the array accordingly.

Defining Functions

  • The correct syntax for defining a function in JavaScript is function name(parameters) { code } or const name = function(parameters) { code }.

For-In Loop

  • The for-in loop in JavaScript returns a string index when used with an array, not a numeric index.

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