Mission Control

Mission control sends a list of commands. Write runMission(commands) that starts with { status: "ready", fuel: 0, altitude: 0 } and applies each command in order:

{ type: "fuel", amount }: only while ready. Adds fuel, but the tank holds at most 100.
{ type: "launch" }: only while ready and with at least 50 fuel. Status becomes "flying" and uses 50 fuel.
{ type: "burn", amount }: only while flying and with enough fuel. Uses that much fuel and climbs 10 altitude per unit.
{ type: "land" }: only while flying. Status becomes "landed" and altitude returns to 0.

Any command that breaks a rule, or has an unknown type, is rejected: the state stays the same and its index goes in a rejected list. Return the final state with rejected added.

Build it step by step

Loop with commands.forEach((cmd, i) => ...) so you have each index.
Use a switch on cmd.type with one case per command.
Inside each case, check the rules first. If one fails, push i to rejected and stop.
Only change the state when every rule passes.

Examples

runMission([{ type: "fuel", amount: 80 }, { type: "launch" }, { type: "burn", amount: 20 }, { type: "land" }])

→ { status: "landed", fuel: 10, altitude: 0, rejected: [] }

runMission([{ type: "launch" }, { type: "fuel", amount: 60 }, { type: "launch" }])

→ { status: "flying", fuel: 10, altitude: 0, rejected: [0] }

project.js

JAVASCRIPT

Saved as you type

Tests

0 of 5 passing

•
a clean flight
runMission([{ type: "fuel", amount: 80 }, { type: "launch" }, { type: "burn", amount: 20 }, { type: "land" }])
expected { status: "landed", fuel: 10, altitude: 0, rejected: [] }
•
launch without fuel
runMission([{ type: "launch" }, { type: "fuel", amount: 60 }, { type: "launch" }])
expected { status: "flying", fuel: 10, altitude: 0, rejected: [0] }
•
tank caps at 100
runMission([{ type: "fuel", amount: 70 }, { type: "fuel", amount: 70 }])
expected { status: "ready", fuel: 100, altitude: 0, rejected: [] }
•
unsafe burns and odd commands
runMission([{ type: "fuel", amount: 55 }, { type: "launch" }, { type: "burn", amount: 9 }, { type: "fuel", amount: 5 }, { type: "dance" }, { type: "burn", amount: 3 }])
expected { status: "flying", fuel: 2, altitude: 30, rejected: [2, 3, 4] }
•
no commands
runMission([])
expected { status: "ready", fuel: 0, altitude: 0, rejected: [] }

On the line

+600 XP

Pass all 5 tests to claim it.