Question 191992 in Javascript Question posted in
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Javascript – My test.js file isn't outputting anything when i do "node test.js" or anything else

I want to test a simple program with node:

let myArray = [1, 2, 3, 4, 5];
function doubleInput(arrayItem) {
  return arrayItem * 2;
}

But for some reason nothing outputs when i do node.js in the terminal. Am i missing something? I do have node installed (v20.3.0).

My output should be:
2, 4, 6, 8, 10

But sadly, nothing shows up

I simply have just a test.js file that has an array with values and then a function that multiplies by two and returns that result. I tried adding a .npmignore file, a package lock and package.json adding in i still have the same results. Also in terminal i do

node test.js
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3

Answers


  1. 0

    Your code outputs nothing, because you’re not calling your function, and you’re not printing anything.

    I would also suggest using map in your case. You can use it like this:

    let myArray = [1, 2, 3, 4, 5];

result = myArray.map(x => x * 2)

console.log(result);

    Outputs

    [ 2, 4, 6, 8, 10 ]

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  2. 0

    You actually didn’t call your function doubleInput, that’s why you didn’t get any output,
    Even though you invoke it, you gonna get NaN since return arrayItem * 2; is like [1, 2, 3, 4, 5] * 2 which always gives NaN;

    The right way is looping over each value, Doubling it and storing it in an array, and finally returning that variable.

    let myArray = [1, 2, 3, 4, 5];
function doubleInput(arrayItems) {
  let returnedArrayOfItems = [];
  for(let i=0; i<=arrayItems.length-1; i++){
    let arrayItem = arrayItems[i];
    returnedArrayOfItems.push(arrayItem*2);
  }
  return returnedArrayOfItems;
}
console.log(doubleInput(myArray))
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  3. 0

    You can use map method and join

    let myArray = [1, 2, 3, 4, 5];

function doubleInput(array) {
    return array.map(x => 2 * x);
};

let res = doubleInput(myArray);

console.log(res.join(', '));
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