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lois6b
Asked: 2020-02-03 02:57:19 +0800 CST 2020-02-03 02:57:19 +0800 CST

Do not allow " ' " (apostrophe) at the beginning of the word

  • 772

I am making a Regular expression in Javascript to process last names.

I have been asked to be valid:

  • One or more surnames
  • alphabetic characters (with accents), ñ and apostrophe.
  • the apostrophe can go at the end of a surname (Di' Stefan) or in the middle (O'Brian) but not at the beginning ( 'OBrian , O 'Brian )
  • two surnames can be separated by hyphens (Menendez Martin-Vega)

EDIT

  • The last surname cannot end in an apostrophe or hyphen either. Ex: (Menendez- , Fernandez', Martin - , ...)

I made a regex that works in the online debugger.

([a-z\u00E0-\u00FC]+[']?[a-z\u00E0-\u00FC]?[\s-]*)+$

Debugx Demo

But implementing it in javascript doesn't fail on apostrophes at the beginning:

var str = "'Obrian o";
    var patt = new RegExp(/([a-z\u00E0-\u00FC]+[']?[a-z\u00E0-\u00FC]?[\s-]*)+$/i );
    console.log(patt.test(str));

What is the difference between the debugger and my function? How can I achieve the required points?

javascript

1 Answers

  1. Best Answer

    You were simply missing a ^at the beginning of the pattern to tell it to start checking from it. Otherwise, it will start at any position to perform the checks, so the pattern is perfectly fulfilled just after the apostrophe, which is not what you want:

    var cadenas = [
  "'Obrian o",
  "O'brian o",
  "O'brian o'",
  "O'brian oo",
  "O'brian 'o",
  "O'brian '",
  "O'brian o-",
  "Di' Stefan",
  "Di'",
  "O'BrianDi'",
  "O'Brian Di'",
  "Menendez Martin-Vega",
  "Menendez-",
  "Paco Menendez-",
  "Paco -Pelayo",
  "Paco Menendez-Pelayo",
  "Paco Menendez-Pelayo-Torres",
  "Paco Menendez Pelayo",
  "Paco Menendez-Pelayo Torres",
  "Paco Menendez Pelayo Torres",
  "Nombre Fernandez'",
  "Martin -",
];
var patt = new RegExp(
  /^([ -]([a-z][a-z']+|[a-z]+))*([ -]([a-z][a-z']+[a-z]|[a-z]+))$/i
);
for (i in cadenas) {
  var resultado = patt.test(" " + cadenas[i].trim());
  var parrafo = document.createElement("p");
  parrafo.className = resultado;
  var texto = document.createTextNode(
    cadenas[i] + ": " + resultado
  );
  parrafo.appendChild(texto);
  document.body.appendChild(parrafo);
}
    .true {
  color: green;
}
.false {
  color: red;
}
p {
  margin: 0px;
}

    Now the pattern is more complex and separated into two parts:

    • Checking the first surnames.
    • Last surname check.

    An improvement, to improve debugging and make any modification easier:

    function comprobacion(apellidos) {
  /* Patrón para todos los apellidos menos el último */
  var pat_ini = new RegExp(
    /^([a-z][a-z']+)$/i
  );
  /* Patrón para el último apellido */
  var pat_fin = new RegExp(
    /^([a-z][a-z']+[a-z]|[a-z]+)$/i
  );
  var partes = apellidos.split(/[ -]/);
  /* Comprobamos todos los apellidos menos el último */
  for (var i = 0; i < partes.length - 1; i++) {
    /* Si no coincide, informamos de ello */
    if (pat_ini.test(partes[i]) === false) {
      return false;
    }
  }
  /* Devolvemos la comprobación del último apellido */
  return pat_fin.test(partes[i]);
}

var cadenas = [
  "'Obrian o",
  "O'brian o",
  "O'brian o'",
  "O'brian oo",
  "O'brian 'o",
  "O'brian '",
  "O'brian o-",
  "Di' Stefan",
  "Di'",
  "O'BrianDi'",
  "O'Brian Di'",
  "Menendez Martin-Vega",
  "Menendez-",
  "Paco Menendez-",
  "Paco -Pelayo",
  "Paco Menendez-Pelayo",
  "Paco Menendez-Pelayo-Torres",
  "Paco Menendez Pelayo",
  "Paco Menendez-Pelayo Torres",
  "Paco Menendez Pelayo Torres",
  "Nombre Fernandez'",
  "Martin -",
];
/* Comprobamos cada una de las cadenas del test */
for (i in cadenas) {
  var resultado = comprobacion(cadenas[i]);
  var parrafo = document.createElement("p");
  parrafo.className = resultado;
  var texto = document.createTextNode(
    cadenas[i] + ": " + resultado
  );
  parrafo.appendChild(texto);
  document.body.appendChild(parrafo);
}
    .true {
  color: green;
}
.false {
  color: red;
}
p {
  margin: 0px;
}

    Another method in which, to simplify the regular expression, we check each of the last names in parts. Note the detail that, in case of only having a last name, the loop that checks the pattern pat_iniwill never be executed.

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