Take the last position of a split()

Question

I need to enter a name in an input and display the person’s name in the following format:

SURNAME(last position), So-and-so.

But I’m not being able to show the name in this format, and I’m also not being able to use the . toUpperCase() in the "last" variable as it is giving error.

function formatar() {
  var nome = document.getElementById("nome").value;

  if (nome === "" || Number(nome)) {
    alert("Digite seu nome corretamente");
    document.getElementById("nome").value = "";
    document.getElementById("nome").focus();
    return;
  }

  var partes = nome.split(" ");
  var tam = partes.length;
  var text;
  var ultimo = partes.slice(-1);
  console.log(ultimo);

  for (i = 0; i < tam; i++) {
    text = ultimo.toUpperCase() + ", " + partes;

  }
  document.getElementById("formatacao").innerHTML = text;

}

<input id="nome">
<button type="button" onclick="formatar()">Formatar</button>
<div id="formatacao"></div>

Answer 1

Suggestion:

var partes = nome.split(' ');
var formatado = [partes.pop().toUpperCase(), partes.join(' ')].join(', ');

The idea is:

• separate by spaces (as you already had)
• create an array with 2 positions
• in the first position partes.pop().toUpperCase() (the last part with large letter)
• in the second position put the rest, re-placing the spaces
• join the parts with comma and space

Example:

function formatar() {
  var nome = document.getElementById("nome").value;

  if (nome === "" || Number(nome)) {
    alert("Digite seu nome corretamente");
    document.getElementById("nome").value = "";
    document.getElementById("nome").focus();
    return;
  }

  var partes = nome.split(' ');
  var formatado = [partes.pop().toUpperCase(), partes.join(' ')].join(', ');

  document.getElementById("formatacao").innerHTML = formatado;

}

document.querySelector("button").addEventListener('click', formatar);

input {
  width: 100%;
  padding: 10px;
}

<input id="nome" type="text" value="Antonio Manuel Antunes" />
<button>Formatar</button>
<div id="formatacao"></div>

Answer 2

Approach using regex:

var nome = "Jose da Silva Sauro";

function replacer(match, m1, m2){
    return m2.toUpperCase() + ', ' + m1;
}

nome.replace(/^(.+)\b(\w+)$/g, replacer); // "SAURO, Jose da Silva"

Answer 3

With the split divide, and then take the last with length-1 and joins with the whole array except the last one, using the slice to cut the last and the join to unite everything again with spaces:

var nome = "Luis Carlos Teixeira";
var nomes = nome.split(" ");
var nomeFinal = nomes[nomes.length-1].toUpperCase() + ", " + nomes.slice(0,-1).join(" ");

console.log(nomeFinal);

In your code ultimo.toUpperCase() gives error because last is an array and not a string. Remember that last Slice returns an array.

In the functions used we have:

• split(" ") breaks a string into an array according to the separator past tense
• slice(0, -1) gets the whole array except the last element
• join (" ") unites the whole array with spaces forming a new text(string)

Answer 4

I improved its function to test numerical names since it was inserted 123 456 789 or Fulano de Tal 123would accept. Credits - Sergio

function formatar() {
  var nome = document.getElementById("nome").value;
  var partes = nome.split(' ');
  var tam = (partes.length-1);

  var ultimo = partes.slice(-1);
  console.log(ultimo);
  ultimo = ultimo.toString();
  
  var HasNumericStrings = partes.filter(function(i) {
    return !isNaN(i);
  }).length > 0;

  if (HasNumericStrings) {
    alert("Digite seu nome corretamente");
    document.getElementById("nome").value = "";
    document.getElementById("nome").focus();
  } else {
    document.getElementById("formatacao").innerHTML = ultimo.toUpperCase() + ", " + partes.slice(0,-1).join(" ");
  }

}
document.querySelector("button").addEventListener('click', formatar);

<input id="nome" type="text" value="Fulano de Tal" />
<button>Formatar</button>
<div id="formatacao"></div>

• The method split() splits a String object into an array of strings by separating the string into substrings
• The estate length defines the number of elements of the matrix. It is a number one unit greater than the highest element defined in a matrix.
• The method filter() creates a new array with all the elements that passed the test implemented by the provided function. Read more
• The method toUpperCase returns a string where all alphabetic characters have been capitalized.

• The method join(separador) joins all array elements within a string. separador is optional. Specifies a string to separate each element of the array. The separator is converted into a string if necessary. If omitted, the array elements are separated with a comma. If the separator is an empty string, all elements are joined with no character between them.

  In the case in question we use a space join(" ") Read more

Answer 5

Only one variant of the elegant solution @J.Guilherme(+1):

var n = "Jose da Silva Sauro";
n = n.replace(/(.+) (\w+)$/, function(_,a,b){return b.toUpperCase()+ ", "+ a});