Question 258842 in Javascript Question posted in
A very good W3school tutorial can be found here.

Javascript – Making new strings with array data

I am trying to solve this problem where if age > 18 it returns name + can go to the matrix or if age < 18 returns they are under age:

function makeStrings(arr){
  // your code here
}

console.log(makeStrings([
    {
        name: "Angelina Jolie",
        age: 80
    },
    {
        name: "Eric Jones",
        age: 2
    },
    {
        name: "Paris Hilton",
        age: 5
    },
    {
        name: "Kayne West",
        age: 16
    },
    {
        name: "Bob Ziroll",
        age: 100
    }
])); 
// ["Angelina Jolie can go to The Matrix", 
// "Eric Jones is under age!!", 
// "Paris Hilton is under age!!", 
// "Kayne West is under age!!", 
// "Bob Ziroll can go to The Matrix"]

The exercise is from a list of array.prototype.map() exercises so although I think there are other ways to get the correct answer I’ve tried to use the map() method. So far all I’ve managed to get back is a syntax error or [undefined,undefined,undefined,undefined,undefined] which is what the code below returns.

function makeStrings(arr){
  // your code here
  const map1 = arr.map((person) => {
    if(person.age > 18){
      person.name + " can go to The Matrix";
    }
    else {
      person.name + "is underage!!";
    }
  });
  return map1;
}

console.log(makeStrings([
    {
        name: "Angelina Jolie",
        age: 80
    },
    {
        name: "Eric Jones",
        age: 2
    },
    {
        name: "Paris Hilton",
        age: 5
    },
    {
        name: "Kayne West",
        age: 16
    },
    {
        name: "Bob Ziroll",
        age: 100
    }
])); 
// ["Angelina Jolie can go to The Matrix", 
// "Eric Jones is under age!!", 
// "Paris Hilton is under age!!", 
// "Kayne West is under age!!", 
// "Bob Ziroll can go to The Matrix"]
Tags:

2

Answers


  1. 0

    You can use map() to transform the array of objects. However, there’s a small mistake in your callback function. You’re not returning the string in your map() callback.

    Here’s the corrected code:

    function makeStrings(arr){
  const map1 = arr.map((person) => {
    if(person.age > 18){
      return person.name + " can go to The Matrix";
    }
    else {
      return person.name + " is under age!!";
    }
  });
  return map1;
}

    In your original code, you were missing the return statement before person.name + ..., so the map callback didn’t return anything, resulting in undefined.

    With this corrected code, when you run makeStrings with the provided array, you should get the desired output:

    [
  "Angelina Jolie can go to The Matrix",
  "Eric Jones is under age!!",
  "Paris Hilton is under age!!",
  "Kayne West is under age!!",
  "Bob Ziroll can go to The Matrix"
]
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  2. 0 
    function makeStrings(arr) {
  const result = [];

  for (const person of arr) {
    if (person.age >= 18) {
      result.push(`${person.name} can go to The Matrix`);
    } else {
      result.push(`${person.name} is under age!!`);
    }
  }

  return result;
}

console.log(makeStrings([
    {
        name: "Angelina Jolie",
        age: 80
    },
    {
        name: "Eric Jones",
        age: 2
    },
    {
        name: "Paris Hilton",
        age: 5
    },
    {
        name: "Kayne West",
        age: 16
    },
    {
        name: "Bob Ziroll",
        age: 100
    }
]));

    you should try

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