How to return array element based on input index location-CodePudding

I'm trying to return the teacher's name based on what classroom the students name is in. teacher[0] is responsible for rooms[0] and teacher[1] is responsible for rooms[1] and so on.

let teachers = ["Arrington", "Kincart", "Alberts", "Pickett"]

let rooms = [
  ["Andy", "Rodolfo", "Lynn", "Talia"],
  ["Al", "Ross", "Jorge", "Dante"],
  ["Nick", "Kim", "Jasmine", "Dorothy"],
  ["Adam", "Grayson", "Aliyah", "Alexa"]
]

let whichTeacher = (student) => {
    return rooms.findIndex(row => row.indexOf(student) !== - 1)
    
}


console.log(`The teacher who has Jorge is ${whichTeacher("Jorge")}.`)
console.log(`The teacher who has Alexa is ${whichTeacher("Alexa")}.`)

the current output is

The teacher who has Jorge is 1.
The teacher who has Alexa is 3.

so I know im close but I cant figure out how to output the teachers name instead of its index number.

CodePudding user response：

You forgot to use your teachers array. By indexing it you can achieve what you want:

let teachers = ["Arrington", "Kincart", "Alberts", "Pickett"]


let rooms = [
  ["Andy", "Rodolfo", "Lynn", "Talia"],
  ["Al", "Ross", "Jorge", "Dante"],
  ["Nick", "Kim", "Jasmine", "Dorothy"],
  ["Adam", "Grayson", "Aliyah", "Alexa"]
]

let whichTeacher = (student) => {
    return teachers[rooms.findIndex(row => row.indexOf(student) !== - 1)]
    //             ^ use the found index to index the teachers array
}


console.log(`The teacher who has Jorge is ${whichTeacher("Jorge")}.`)
console.log(`The teacher who has Alexa is ${whichTeacher("Alexa")}.`)

CodePudding user response：

You can just get the teacher at this index of the teachers array :

const teachers = ["Arrington", "Kincart", "Alberts", "Pickett"]
const rooms = [
  ["Andy", "Rodolfo", "Lynn", "Talia"],
  ["Al", "Ross", "Jorge", "Dante"],
  ["Nick", "Kim", "Jasmine", "Dorothy"],
  ["Adam", "Grayson", "Aliyah", "Alexa"]
]
const whichTeacher = student => teachers[ rooms.findIndex(row => row.includes(student)) ]


console.log(`The teacher who has Jorge is ${ whichTeacher("Jorge") }.`)
console.log(`The teacher who has Alexa is ${ whichTeacher("Alexa") }.`)

(btw : prefer using const instead of let whenever its possible (even more for arrow functions) and use the built-ins when you can (like Array.prototype.includes instead of array.indexOf(...) != -1) for clarity and sometimes for performances)