# Exercises: Booleans and Conditionals

Attempt these exercises to test your understanding. Don’t worry if you struggle while working on them. Struggling and then reviewing the material will help you remember it.

Take note of any problem here or topic from this chapter that you don’t understand. Take a break and return to the problem. Do you see it in a new way or have a better understanding? If not, try spending five minutes researching the topic. Start with this book and if you still have questions, ask one on the internet or Slack/Discourse. You’re not the first person to learn to code and you’re definitely not the first person to ask a question or get stuck!

1. Declare and initialize the following variables for our space shuttle
Variable NameValue
spaceSuitsOntrue
computerStatusCode200
shuttleSpeed15000
1. Examine the code below. What will be printed to the console?

Use the value of `engineIndicatorLight` defined above to answer this question.

``````if (engineIndicatorLight === "green") {
console.log("engines have started");
} else if (engineIndicatorLight === "green blinking") {
console.log("engines are preparing to start");
} else {
console.log("engines are off");
}
``````
2. Write conditional expressions to satisfy the safety rules.

Use the variables defined from the table above to satisfy the rules listed below.

• `crewStatus`

• If the value is `true`, print “Crew Ready”
• Else print “Crew Not Ready”
• `computerStatusCode`

• If the value is `200`, print “Please stand by. Computer is rebooting.”
• Else if the value is `400`, print “Success! Computer online.”
• Else print “ALERT: Computer offline!”
• `shuttleSpeed`

• If the value is `> 17500`, print “ALERT: Escape velocity reached!”
• Else if the value is `< 8000`, print “ALERT: Cannot maintain orbit!”
• Else print “Stable speed”
1. PREDICT

Do these code blocks produce the same result? Answer Yes or No.

``````if (crewStatus && computerStatusCode === 200 && spaceSuitsOn) {
console.log("all systems go");
} else {
}
``````
``````if (!crewStatus || computerStatusCode !== 200 || !spaceSuitsOn) {
} else {
console.log("all systems go");
}
``````
2. Monitor the shuttle’s fuel status.

Implement the checks below using `if` / `else if` / `else` statements. Order is important when working with conditionals, and the checks below are NOT written in the correct sequence. Please read ALL of the checks before coding and then decide on the best order for the conditionals.

• If `fuelLevel` is above 20000 AND `engineTemperature` is at or below 2500, print “Full tank. Engines good.”
• If `fuelLevel` is above 10000 AND `engineTemperature` is at or below 2500, print “Fuel level above 50%. Engines good.”
• If `fuelLevel` is above 5000 AND `engineTemperature` is at or below 2500, print “Fuel level above 25%. Engines good.”
• If `fuelLevel` is at or below 5000 OR `engineTemperature` is above 2500, print “Check fuel level. Engines running hot.”
• If `fuelLevel` is below 1000 OR `engineTemperature` is above 3500 OR `engineIndicatorLight` is red blinking, print “ENGINE FAILURE IMMINENT!”
• Otherwise, print “Fuel and engine status pending…”
1. Final bit of fun!

The shuttle should only launch if the fuel tank is full and the engine check is OK. However, let’s establish an override command to ignore any warnings and send the shuttle into space anyway!

• Create the variable `commandOverride`, and set it to be `true` or `false`.

If `commandOverride` is `false`, then the shuttle should only launch if the fuel and engine check are OK.

If `commandOverride` is `true`, then the shuttle will launch regardless of the fuel and engine status.

• Code the following `if` / `else` check:

If `fuelLevel` is above 20000 AND `engineIndicatorLight` is NOT red blinking OR `commandOverride` is true print “Cleared to launch!”

Else print “Launch scrubbed!”