CodeHS Answers: Unit 4 : If Statements

4.1.5: Is There a Ball?

// Karel should put a ball on the first spot // if there isn't one already there and then move. function start() { if(noBallsPresent()){ putBall(); } move(); }

Which general if statement definition is written correctly?

B

What does an if/else statement look like in JavaScript?

D

Why do we use if statements in JavaScript?

To do something only if a condition is true

Why do we use if/else statements in JavaScript?

To either do something if a condition is true or do something else

4.3.1: Face the Right Direction

function start() { if(noBallsPresent()){ turnAround(); } else { turnRight(); } }

4.2.4: One Ball in Each Spot

function start(){ checkBall(); move(); checkBall(); move(); checkBall(); move(); checkBall(); } function checkBall(){ if(noBallsPresent()){ putBall(); } }

4.2.5: Right Side Up

function start(){ if (facingSouth()) { turnRight(); } if (facingWest()) { turnAround(); } }

4.3.2: Fetch Puzzle

function start(){ if(facingEast()){ move(); takeBall(); } if(ballsPresent()){ takeBall(); } if( facingWest()){ turnAround(); } }

4.1.3: If Statements

function start(){ move(); if(frontIsClear()){ move(); } } /* You can try commenting in this start function to see what happened before. If we try to move twice here, then karel will crash into a wall. function start(){ move(); move(); } */

4.2.3: If/Else Statements

function start(){ move(); if(frontIsClear()){ move(); }else{ turnLeft(); } }

4.1.4: Safe Take Ball

function start(){ safeTakeBall(); move(); safeTakeBall(); } function safeTakeBall(){ if(ballsPresent()){ takeBall(); } }