Module #4: Principles of Development Flashcards

Question

What does the return statement do in JavaScript?

Answer 1

–Ends a function and sends back a value –Used to output a result from a function

Answer 2

–A function applies one or more rules to an input to produce an output –Input: the value you give the function –Output: the result the function gives back –We say that f(x) returns the value of y

Answer 3

general structure function name(parameter1, parameter2, parameter3) { // code to be executed } For example: // Function to compute the product of p1 and p2 function myFunction(p1, p2) { return p1 * p2; } JavaScript Functions (w3sc

Answer 4

function convertToCelcius(degrees_fahrenheit){ var the_answer = (degrees_fahrenheit - 32) * ( 5 / 9 ); return the_answer; }

Answer 5

–Use line-of-code breakpoints Open the Sources tab Open the file containing your code Go to the line you want to pause at Click the line number → a blue icon will appear –This lets you debug and inspect your code step-by-step

Answer 6

–Break complex problems into smaller parts (divide & conquer) –Give meaningful names to reusable blocks of code –Avoid repeating the same code over and over –Use the same function with different inputs (arguments) to get different results

Answer 7

–Defining a function: –You create the function using the function keyword –Example: function greet (name) { return "Hello " + name; } –Calling a function: –You run the function by using its name with parentheses –Example: greet("Carl");

Answer 8

–If the value is in quotes, it’s a String → 'Your car is getting ' + MPG + ' MPG.' → String –If the value is the result of math, it’s a Number → miles / gas → Number –If a function returns a value, look at what’s being returned → return miles / gas; → returns a Number → return 'Your car is getting ' + MPG + ' MPG.'; → returns a String

Answer 9

–A Boolean is always either true or false –You can assign it directly: var x = true; –Or use a comparison, which returns a Boolean: –a == b returns true if a equals b, else false –Used in conditions, logic, and control flow

Answer 10

–Use comparison operators to evaluate relationships –Each comparison returns a Boolean (true or false) –Key operators: –== → equal to –!= → not equal to –> → greater than –< → less than –>= → greater than or equal to –<= → less than or equal to

Answer 11

–Use if (condition) to run code only if the condition is true –The condition uses a comparison (e.g., >=, ==) –Use = for assignment, not comparison –Code inside {} only runs if the condition is true –Always use ; to end each statement structure = if(condition) { ...}

Answer 12

–Use an if inside another if to check multiple conditions in sequence –The inner block only runs if the outer condition is true –Useful for situations with dependent logic (e.g., age AND gender) General structure: if (condition1) { // Code runs if condition1 is true if (condition2) { // Code runs if condition1 AND condition2 are true } }

Answer 13

Q: What is the general rule and structure for using if and else statements in JavaScript? –Use if to run code only if a condition is true –Use else to run code when the condition is false –Allows you to choose between two code blocks General structure: if (condition) { // code runs if condition is true } else { // code runs if condition is false }

Answer 14

–Use if...else if...else when you want only one block to run –JavaScript checks conditions top-down, stops at the first true –This is called short-circuiting General structure: if (condition1) { // runs if condition1 is true } else if (condition2) { // runs if condition1 is false AND condition2 is true } else { // runs if none of the above are true }

Answer 15

–Each if is independent –All true conditions run, not just the first one –This can cause logic errors if conditions overlap General structure: if (condition1) { // runs if condition1 is true } if (condition2) { // also runs if condition2 is true }

Answer 16

–Use isNaN() to check if a value is "Not-a-Number" –Returns true if the value is not a valid number –Automatically tries to convert the value to a number before checking General structure: isNaN(expression) // returns true or false Examples: –isNaN("123.45") → false (valid number) –isNaN("zebra") → true (not a number) –isNaN(0) → false (number) –isNaN("$30") → true (not a number)

Answer 17

–Use if (isNaN(value)) to check for invalid (non-numeric) input –Use return inside the if block to exit early and skip the rest of the function –This helps prevent bad data from being processed General structure: function someFunction(input) { if (isNaN(input)) { return 'Bad input'; } // Continue with the rest of the logic if input is valid }

Answer 18

–Use if to run code when a condition is true –Use else to run code when the condition is false –Use else if to test a new condition if the previous one is false General structure: javascript Copier Modifier if (condition1) { // runs if condition1 is true } else if (condition2) { // runs if condition1 is false AND condition2 is true } else { // runs if none of the above conditions are true }

Answer 19

–Use a for loop when you want to repeat a block of code a specific number of times –The loop has three parts: 1. Initialization (e.g., let i = 0) 2. Condition (loop runs while this is true) 3. Increment (e.g., i++ increases the counter) General structure: for (initialization; condition; increment) { // code to repeat } Example: for (var x = 1; x <= 3; x++) { console.log(x); }

Answer 20

–The variable declared in the loop (e.g., x) is stored in memory and updated each time the loop runs –At the start, the memory holds the initial value (e.g., x = 1) –Each loop cycle, the value is incremented (e.g., x = 2, then x = 3, etc.) –Once the loop condition is false, the loop stops and memory stops updating General structure reminder: for (var x = 1; x <= 3; x++) { console.log(x); } This explains how x changes from 1 → 2 → 3 → (stops at 4 because x <= 3 becomes false).

Answer 21

–Use a running total variable (e.g., sumOfNumbers) initialized before the loop –Inside the loop, update the total using: sumOfNumbers = sumOfNumbers + counter; –A loop counter is used to control the number of times this addition happens –All involved variables (e.g., sumOfNumbers, counter, numberOfLoops) are stored and updated in memory General structure: var sum = 0; for (var i = 1; i <= limit; i++) { sum = sum + i; }

Answer 22

–Start with an initial value (e.g., futureValue = investment) –Use a for loop that runs once for each compounding period –Each loop iteration increases the future value by a percentage of itself –This is done using: futureValue += futureValue * annualRate / 100; Alternative forms: futureValue = futureValue + (futureValue * (annualRate / 100)); futureValue = futureValue * (1 + (annualRate / 100)); General structure: var futureValue = startingAmount; for (var i = 1; i <= years; i++) { futureValue = futureValue * (1 + rate / 100); }

Answer 23

–Use a for loop to repeat code multiple times –Each iteration outputs a line of text using console.log() or document.write() –Useful for patterns, menus, repeated instructions, etc. General structure: for (var i = 1; i <= numberOfLines; i++) { console.log("This is line " + i); }

Answer 24

–A loop can be placed inside another loop –The inner loop runs completely every time the outer loop runs once –Used to handle rows and columns, tables, or combinations General structure: for (var i = 1; i <= outerLimit; i++) { for (var j = 1; j <= innerLimit; j++) { console.log("i = " + i + ", j = " + j); } }

Answer 25

–Performing calculations that require repetition (e.g., compound interest, sums) –Generating repetitive content, including HTML elements like: –< table> rows –< select> options –< ul> or < ol> list items –Often used with conditionals and functions for more complex logic

Module #4: Principles of Development Flashcards

(49 cards)