Variable to validate 'Login' field?

When you use ^ inside brackets ( [] ), you're saying you do not want the characters that are in the brackets - this expression is also called Negated Character Class .

But if you want an expression that accepts only letters (lowercase and uppercase) and numbers, you should remove the% with% of the brackets and put the characters you need inside them.

In addition, it would be interesting to put a ^ at the beginning (outside the brackets, at the beginning, means "beginning of the string"), and a ^ at the end (meaning "end of string"). p>

I also put a% quantifier with% meaning "one or more occurrences". The final expression looks like this:

var padrao = /^[a-zA-Z0-9]+$/;

console.log(padrao.test('abcABC01')); // true
console.log(padrao.test('ábc')); // tem caractere acentuado, retorna false

• $ is the "start of string" "
• + is "one or more occurrences of lowercase letters ( ^ ), uppercase ( [a-zA-Z0-9]+ ) or numbers ( a-z )"
• A-Z is the "end of string"

That is, it checks to see if all the characters in the string are letters or numbers.

• The% circumflex ^ marks the beginning of a line
• The dollar sign $ marks the end of a line
• i is case sensitive,
• [a-z] letters in the range of a to z , when we have a dash - between two characters, this represents the entire range between them
• [] set, any character included in the set, including space

var validacao = /^[a-záàâãéèêíïóôõöúçñ]+$/i
var nomes = ["Fulano", "Fulano com espaços", "Céçlañô", "ze234", "FulanoSemEspaçosComcecedilha", "FulanoSemEspacosSemcecedilha"]
nomes.forEach(function(nome) {
    console.log(nome + ": " + validacao.test(nome))
});

  

Within the set you can set the allowed letters:)

Finally

For your case, just numbers and letters, uppercase or lowercase

var validacao = /^[a-z0-9]+$/i
var nomes = ["Fulano", "Fulano com espaços", "Céçlañô", "ze234", "FulanoSemEspaçosComcecedilha", "FulanoSemEspacosSemcecedilha"]
nomes.forEach(function(nome) {
    console.log(nome + ": " + validacao.test(nome))
});

  

As mentioned earlier, the i modifier is used to perform case-insensitive matching.

Another way:

var validacao = /^[a-z\d]+$/i
var nomes = ["Fulano", "Fulano com espaços", "Céçlañô", "ze234", "FulanoSemEspaçosComcecedilha", "FulanoSemEspacosSemcecedilha"]
nomes.forEach(function(nome) {
    console.log(nome + ": " + validacao.test(nome))
});

  

\d same as [0-9]

We can further reduce the expression

var validacao = /^[\w]+$/
var nomes = ["Fulano", "Fulano com espaços", "Céçlañô", "ze234", "FulanoSemEspaçosComcecedilha", "FulanoSemEspacosSemcecedilha", "tudominusculas", "TUDOMAIUSCULAS"]
nomes.forEach(function(nome) {
    console.log(nome + ": " + validacao.test(nome))
});

  

\w - alfanuerico