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Questions and Answers
What will be the result of the expression $3 / 0$ in JavaScript?
What will be the result of the expression $3 / 0$ in JavaScript?
Which of the following is a common mathematical constant in JavaScript that represents the ratio of the circumference of a circle to its diameter?
Which of the following is a common mathematical constant in JavaScript that represents the ratio of the circumference of a circle to its diameter?
Which of the following functions in JavaScript can be used to round a number to the nearest integer?
Which of the following functions in JavaScript can be used to round a number to the nearest integer?
Which mathematical function would you use in JavaScript to find the sine of a number?
Which mathematical function would you use in JavaScript to find the sine of a number?
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What method would you use to generate a random number between 0 and 1 in JavaScript?
What method would you use to generate a random number between 0 and 1 in JavaScript?
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Which of the following statements about accessing array values is correct?
Which of the following statements about accessing array values is correct?
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What would be the output of accessing the value at index 2 in the groceries array?
What would be the output of accessing the value at index 2 in the groceries array?
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Which symbol is used to denote the start and end of an array in JavaScript?
Which symbol is used to denote the start and end of an array in JavaScript?
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If the groceries array is defined as var groceries = ['Milk', 'Eggs'], what will groceries[1] return?
If the groceries array is defined as var groceries = ['Milk', 'Eggs'], what will groceries[1] return?
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Which of these operations would yield an error when working with an array?
Which of these operations would yield an error when working with an array?
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How do you create a non-empty array in JavaScript?
How do you create a non-empty array in JavaScript?
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What is the index value of 'Salami' in the groceries array defined as var groceries = ['Milk', 'Eggs', 'Frosted Flakes', 'Salami', 'Juice'];?
What is the index value of 'Salami' in the groceries array defined as var groceries = ['Milk', 'Eggs', 'Frosted Flakes', 'Salami', 'Juice'];?
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What does accessing an index beyond the length of an array return?
What does accessing an index beyond the length of an array return?
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Which method is used to add an item to the end of an array?
Which method is used to add an item to the end of an array?
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What will the groceries array contain after executing groceries.push('Cookies'); with an initial length of 5?
What will the groceries array contain after executing groceries.push('Cookies'); with an initial length of 5?
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What happens to the index values of existing items when using unshift to add an item?
What happens to the index values of existing items when using unshift to add an item?
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What will the result of groceries.pop() if the groceries array has 6 items?
What will the result of groceries.pop() if the groceries array has 6 items?
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If groceries.unshift('Bananas') is called, what is the new value of groceries[0]?
If groceries.unshift('Bananas') is called, what is the new value of groceries[0]?
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What does the length property of an array return?
What does the length property of an array return?
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Which method is appropriate to remove the first item from the array?
Which method is appropriate to remove the first item from the array?
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How can you determine the total number of items in an array given its length property?
How can you determine the total number of items in an array given its length property?
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Which statement is true regarding the push and unshift methods?
Which statement is true regarding the push and unshift methods?
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What will be the result of trying to access groceries[5] in an array defined as var groceries = ['Milk', 'Eggs', 'Frosted Flakes', 'Salami', 'Juice'];?
What will be the result of trying to access groceries[5] in an array defined as var groceries = ['Milk', 'Eggs', 'Frosted Flakes', 'Salami', 'Juice'];?
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Which of the following correctly represents the method used to add multiple items to the end of an array at once?
Which of the following correctly represents the method used to add multiple items to the end of an array at once?
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If you have an array defined as var groceries = ['Milk', 'Eggs']; and you execute groceries.unshift('Yogurt'), what will groceries[0] now return?
If you have an array defined as var groceries = ['Milk', 'Eggs']; and you execute groceries.unshift('Yogurt'), what will groceries[0] now return?
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Which method would you use to remove the last item from the groceries array?
Which method would you use to remove the last item from the groceries array?
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Given var groceries = ['Milk', 'Eggs', 'Frosted Flakes', 'Salami', 'Juice']; what will the result of groceries.length be?
Given var groceries = ['Milk', 'Eggs', 'Frosted Flakes', 'Salami', 'Juice']; what will the result of groceries.length be?
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Which of these statements regarding the creation of an array is correct?
Which of these statements regarding the creation of an array is correct?
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If groceries is defined as var groceries = ['Milk', 'Eggs', 'Salami'], what will the result of groceries.push('Juice'); followed by groceries[3] be?
If groceries is defined as var groceries = ['Milk', 'Eggs', 'Salami'], what will the result of groceries.push('Juice'); followed by groceries[3] be?
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What will be the content of the variable goodAndBad after executing the statement var goodAndBad = good.concat(bad);?
What will be the content of the variable goodAndBad after executing the statement var goodAndBad = good.concat(bad);?
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If you want to increment the variable stooges by 2 in JavaScript, which of the following statements is correct?
If you want to increment the variable stooges by 2 in JavaScript, which of the following statements is correct?
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In the operation var remainder = total % 7, what does the '%' operator compute?
In the operation var remainder = total % 7, what does the '%' operator compute?
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Given the expression var more = (1 + average * 10) / 5, which order of operations is being applied?
Given the expression var more = (1 + average * 10) / 5, which order of operations is being applied?
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Which of the following statements correctly defines the result of the statement i = i - 2?
Which of the following statements correctly defines the result of the statement i = i - 2?
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What will be the index value of the last item after applying the pop method on an array with 7 items?
What will be the index value of the last item after applying the pop method on an array with 7 items?
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What happens to the total number of items in the array after using the push method?
What happens to the total number of items in the array after using the push method?
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If groceries is an array with 4 items, what will be the value of groceries.length if we apply unshift to add an item?
If groceries is an array with 4 items, what will be the value of groceries.length if we apply unshift to add an item?
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Which method would correctly remove the first item from the groceries array?
Which method would correctly remove the first item from the groceries array?
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If you call groceries.pop() on an empty array, what will the result be?
If you call groceries.pop() on an empty array, what will the result be?
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What will the state of the groceries array be after executing groceries.unshift('Apples'); assuming it had 3 items?
What will the state of the groceries array be after executing groceries.unshift('Apples'); assuming it had 3 items?
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When using the length property on an array, what does it actually count?
When using the length property on an array, what does it actually count?
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If you have an array defined as var groceries = ['Bread', 'Milk'], what will running groceries.unshift('Eggs') result in?
If you have an array defined as var groceries = ['Bread', 'Milk'], what will running groceries.unshift('Eggs') result in?
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What value does the groceries array hold after executing groceries.push('Chips') on an initially empty array?
What value does the groceries array hold after executing groceries.push('Chips') on an initially empty array?
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What will be the output of groceries.pop() if the array has the elements ['Fish', 'Meat', 'Vegetables']?
What will be the output of groceries.pop() if the array has the elements ['Fish', 'Meat', 'Vegetables']?
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Study Notes
Advanced Web Programming - Chapter 9: Arrays, Numbers
- Arrays: Used to handle lists of data
- Array Tasks: Can perform common tasks using various array properties
- Numbers: Understand the variety of numerical values encountered
- Math Object: Useful for mathematical operations
Arrays
- Concept: A list of items, similar to a numbered list on paper
- Real-World Example: A grocery list
- Elements: The items in the list
- Array Values: The individual items in the array
Creating Arrays
-
Empty Array:
var groceries = []; -
Literal Notation: Using brackets and commas to specify elements:
var groceries = ["Milk", "Eggs", "Frosted Flakes"];
Accessing Array Values
- Index Values: Each item in an array has a numerical index (starting from 0).
-
Example:
groceries[1]accesses the second array element - Using Index Values: Specify the index value within square brackets to access the element
Accessing Array Values (Continued)
-
Looping: Use
forloops to access all items programmatically -
length Property: The array's
lengthproperty provides the number of elements in the array. Iterating from 0 up tolength - 1.
Adding Items to an Array
-
push(): Adds elements to the end of the array:
Groceries.push("Cookies"); -
unshift(): Adds elements to the beginning of the array:
groceries.unshift("Bananas");- Both
push()andunshift()return the new length of the array.
- Both
Removing Items from an Array
- pop(): Removes and returns the last element in the array
- shift(): Removes and returns the first element in the array
Removing Items from an Array (Continued)
- slice(): A method to copy a portion of an array to a new array, without changing the original.
Finding Items in an Array
- indexOf(): Returns the index of the first occurrence of a given element in the array, or -1 if not found
- lastIndexOf(): Returns the index of the last occurrence of a given element in the array, or -1 if not found.
Merging Arrays
- concat(): Used to combine two or more arrays into a new array.
Numbers (Using a Number)
-
Declaration Examples:
-
var stooges = 3; -
var pi = 3.14159; -
var color = 0xFF; -
var massOfEarth = 5.9742e+24;
-
Operators - Doing Simple Math
-
Basic Operators:
+,-,*,/,%(addition, subtraction, multiplication, division, modulus) -
Order of Operations: Parentheses
(), Exponents, Multiplication, Division, Addition, Subtraction (PEMDAS)
Incrementing and Decrementing
-
Incrementing: Increasing a variable's value by a specific amount (often 1).
i++ori += 2 -
Decrementing: Decreasing a variable's value by a specific amount (often 1).
i--ori -= 2 - Position of Operator: Affects whether the new value or the old value is returned.
Special Values - Infinity and NaN
-
Infinity: Represents values that are very large. For example:
Math.sqrt(-1). -
NaN: "Not a Number" result from invalid numerical operations like
0/0orMath.sqrt(-1)
The Math Object
- Functions and Constants: Useful tools for complex mathematical operations
-
Examples:
-
Math.floor()(rounds down to the nearest integer) -
Math.ceil()(rounds up to the nearest integer) -
Math.round()(rounds to the nearest integer, handling .5 cases) -
Math.random()(generates a pseudo-random number) -
Math.PI(constant value for pi)
-
Trigonometric Functions
- Radians: Trigonometric functions use radians
-
Examples:
-
Math.sin(),Math.cos(),Math.tan(),Math.acos(),Math.asin(),Math.atan()
-
Powers and Square Roots
-
Using Math.pow(): Calculating exponents (e.g., 2 to the power of 4:
Math.pow(2,4)) - Using Math.exp(): Calculating Euler's constant (e) to an exponent.
- Using Math.sqrt(): Calculating the square root of a number
Getting the Absolute Value
-
Math.abs(): Returns the absolute value of a number (e.g.,
Math.abs(-5)returns 5).
Random Numbers
- Math.random(): Returns a pseudo-random number between 0 (inclusive) and 1 (exclusive)
Lab
- Links: provide links to external resources for further learning and practice.
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Description
This quiz covers Chapter 9 of Advanced Web Programming, focusing on arrays and numbers. You'll learn about the concept of arrays, how to create them, and how to access their values. Additionally, explore the Math object and its significance in mathematical operations.
