javascript – Exercise getting the position of the array

Question:

I'm doing an exercise but I can't go through all the necessary validations.

Write the function “MedalhaDeAcordoComPosto(number)”, which receives a number as a parameter, using only an “if”.

You have to return the medal that corresponds to the first positions of a competition:

• MedalDeagredoComPosto (1) – "gold"
• MedalDeagredoComPosto (2) – "silver"
• MedalDeagredoComPosto (3) – "bronze"
• MedAgreementWithPost (4) – "nothing"
• MedAgreementWithPost (15) – "nothing"
• MedAgreementWithPost(0) – "nothing"

 var posicoes = ["nada", "ouro", "prata", "bronze"]; function medalhaDeAcordoComPosto(numero){ return posicoes[numero]; } console.log(medalhaDeAcordoComPosto(15));

My biggest question is how to return "nothing" when I pass parameter 0 or greater than 3.

Answer:

Hi @Raphael, it seems to me that your exercise is intended to make you understand two things.

1. That the indices start at 0 .
2. Identify/Work with the size of an Array .
   _Array.length

I see that the first you already killed ,
^{because it is placing as the first element of its Array the string "nada"}

So for you to finish your exercise you just have to check ( if ) using the size of the array ( posicoes.length ).

Important detail, posicoes.length is the number of elements in your Array posicoes , not the index of the last element .
Knowing this, just add the check if( numero >= posicoes.length ) return "nada";

 var posicoes = ["nada", "ouro", "prata", "bronze"]; function medalhaDeAcordoComPosto(numero){ if( numero >= posicoes.length ) return "nada"; return posicoes[numero]; } console.log(0,medalhaDeAcordoComPosto(0)); console.log(1,medalhaDeAcordoComPosto(1)); console.log(2,medalhaDeAcordoComPosto(2)); console.log(3,medalhaDeAcordoComPosto(3)); console.log(4,medalhaDeAcordoComPosto(4)); console.log(5,medalhaDeAcordoComPosto(5)); console.log(15,medalhaDeAcordoComPosto(15));

^{Note: You may need to add a check for negative numbers to the if , leaving +/- like this: if( numero >= posicoes.length || numero < 0)}

Now let's use index 0

In this other example we are going to create an array with just the prizes, so we will have:

var posicoes = ["ouro", "prata", "bronze"];

In your function we will do the following:

• Decrease by 1 the value entered.
  ^{That way if the person calls the function passing the 1 it will treat it as 0 .}

• Make an if to check:

  • if the value is less than 0 , that is, negative and invalid index.
  • OR if the value is greater than the number of elements in the array - 1 , that is, the last index of the array. (posicoes.length-1)

 var posicoes = ["ouro", "prata", "bronze"]; function medalhaDeAcordoComPosto(numero){ numero -= 1; /// ; isso é a msm coisa que `numero = numero - 1;` if( numero < 0 || numero > posicoes.length-1 ) return "nada"; return posicoes[numero]; } console.log(0,medalhaDeAcordoComPosto(0)); console.log(1,medalhaDeAcordoComPosto(1)); console.log(2,medalhaDeAcordoComPosto(2)); console.log(3,medalhaDeAcordoComPosto(3)); console.log(4,medalhaDeAcordoComPosto(4)); console.log(5,medalhaDeAcordoComPosto(5)); console.log(15,medalhaDeAcordoComPosto(15));