Return Array After For Loop

Question

Having a hard time understanding for loops in arrays. Trying to create a Thank You card creator and these are the steps I'm trying to follow:

Create a new, empty array to hold the messages
Iterate through the input array and inside the loop build out the 'thank you' message for each name using string interpolation, then add that message to the new array you created
After the loop finishes and all of the messages have been added to the new array, return the new array.

 const names = []
function writeCards(names, event) {
  for (let i = 0; i < names.length; i++) {
    console.log(`Thank you, ${names[i]} for the wonderful ${event} gift!`);
  return names;
}

Not sure if I'm on the right track. Thanks for your help!

It is probably confusing (you) to have a global variable (const) names that is shadowed by the local names parameter. Use different names to help reduce the risk of confusion. — user2864740
– user2864740, Commented Jan 1, 2022 at 9:39

HelloWorldEngineer · Accepted Answer · 2022-01-01 09:38:00Z

2

I know your question is focused on for loop, but just in case, you might be interested in using map to achieve the desired result in a more concise manner:

const names = ["Joe", "Nina"]

function writeCards(names, event) {
   return  names.map(name=> `Thank you, ${name} for the wonderful ${event} gift!`)
}

console.log(writeCards(names, "birthday"))

answered Jan 1, 2022 at 9:38

HelloWorldEngineer

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Comments

Perrytheplatypus43 · Accepted Answer · 2022-01-01 09:48:39Z

2

You can use Array.push()

function writeCards(names, event) {
  let messages = []
  for (let i = 0; i < names.length - 1; i++) {
    messages.push("Thank you, " + names[i] + " for the wonderful " + event + " gift!")
  }
  return messages;
}

edited Jan 1, 2022 at 9:48

answered Jan 1, 2022 at 9:32

Perrytheplatypus43

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4 Comments

Andy Over a year ago

You're mixing up your standard string concatenation with template strings which is why the output looks weird.

Perrytheplatypus43 Over a year ago

@Andy Output should look fine as long as names is an array of strings and event is a string

Andy Over a year ago

If you do some testing you'd see that isn't the case.

Perrytheplatypus43 Over a year ago

I see I made a typo it should work now, thank you @Andy

Francis C.j Francis · Accepted Answer · 2022-04-19 13:03:54Z

1

well the i had this issue

i had an empty array outside a loop and wanted to update it inside a loop

and finally return an array with alot of indexes

    //ie 
    //let arr = [] 
    //LOOP then runs
    //then console.log(arr) //console shows [1,2,3,4,5,6,7]

this is how you do it

    let arr = []
    let realArray = [1,2,3,4,5] 
    for (let index = 0; index < realArray.length; index++) { 
       const element = realArray[index] 
       arr.push(element)
    }

    console.log(arr)//your arr = 1,2,3,4,5

this is my first answer here

answered Apr 19, 2022 at 13:03

Francis C.j Francis

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Comments

Andy · Accepted Answer · 2022-01-01 10:08:31Z

function writeCards(names, event) {

 // 1) Create a new, empty array to hold the messages.

 // So, this should be done within the function. We want to be
 // able to update this locally-scoped array with the information
 // we get from each name in the array, combined with the event
 const messages = [];

  for (let i = 0; i < names.length; i++) {

    // 2) using string interpolation

    // What's great is that you've already discovered template strings
    // String concatenation has its uses but this far better.
    const message = `Thank you, ${names[i]}, for the wonderful ${event} gift!`;

    // So, instead of logging the message to the console
    // we're going to push it to the messages array
    messages.push(message);
  }

  // 3) After the loop finishes and all of the messages
  // have been added to the new array, return the new array.
  return messages;

}

console.log(writeCards(['Bob', 'Sue'], 'wedding'));

Ashwini Kumar · Accepted Answer · 2022-01-01 10:10:22Z

-1

I would rather suggest to go with @DoneDeal0 answer's.

In case, if you would like to go with for loop, there's one more cleaner way to go with it. You can use forEach() function given by javascript, as it takes two parameters in it, first is the value of each index and second is the index number itself. Note: forEach() is just similar to for(i=0; i<n; i++).

names = ["Robert", "King", "Joey"];

function writeCards(names) {
  let messages = [];
  names.forEach((name, index) => {
    messages.push("Thank you, " + name + " at " + index + " for the wonderful gift");
  });
  return messages;
}

console.log(writeCards(names));

edited Jan 1, 2022 at 10:10

answered Jan 1, 2022 at 9:53

Ashwini Kumar

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16 Comments

VLAZ Over a year ago

Why is forEach cleaner?

Ashwini Kumar Over a year ago

You can have a look at this article -> alligator.io/js/foreach-vs-for-loops. It will clear your doubt

Ashwini Kumar Over a year ago

I mean cleaner in terms of reading and understanding. Suppose if the above example would consist of three nested for loops, then what would you have said? (i.e. i, j, k) I don't think cleaner always means Time complexity & Space complexity

Andy Over a year ago

@kevinSpaceyIsKeyserSöze the callback for forEach accepts an element and an index.

HelloWorldEngineer Over a year ago

@kevinSpaceyIsKeyserSöze forEach actually takes 3 parameters. The item on which you loop, its index, and the reference to the original array.

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