配列に文字列が含まれていない場合

Question

私はユーザー登録ページを作成していますが、配列に一致しないcharは必要ありません。

function create(){ 
var allowed = [ 
"A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","Q","R","S","T","U","V","W","X","Y","Z", 
"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z", 
"1","2","3","4","5","6","7","8","9","0","_","-"]; 

var username = $("#username").val(); 

if (username == ""){ 
document.getElementById("usernameerror").style.color = "red"; 
document.getElementById("usernameerror").innerHTML = " Username cannot be blank."; 
}else{ 

if (username.indexOf(allowed) != -1){ 
document.getElementById("usernameerror").style.color = "red"; 
document.getElementById("usernameerror").innerHTML = " No symbols."; 
}else{ 
document.getElementById("usernameerror").style.color = "blue"; 
document.getElementById("usernameerror").innerHTML = " ✔"; 
} 

} 

} 

私はそれは単純なもの..（ないサブ文字列）

Answer 1

これはまさにregular expressionsが解決するように設計された問題の種類です。この行を交換してみてください：

if (username.indexOf(allowed) != -1){ 

...これで：

if (!/^[a-z0-9_-]*$/i.test(username)) { 

あなたの要件は、あなたが代わりにあなたの正規表現のためにこれを使用させます同様\w metacharacter、と非常によく似ています

/^[\w-]+$/ 

Answer 2

いかがです賭ける：

if (username.match(/[^\w-]/) !== null) { 
 
    console.log('username has non-word characters...'); 
 
}

何ワット\がないため、ここを参照してください：MDN Regular Expression。

Answer 3

チェックこのアウト：

if (/^[a-z0-9\-\_]+$/.test(username)) { 
    document.getElementById("usernameerror").style.color = "red"; 
    document.getElementById("usernameerror").innerHTML = " No symbols."; 
}else{ 
    document.getElementById("usernameerror").style.color = "blue"; 
    document.getElementById("usernameerror").innerHTML = " ✔"; 
}