RegEx for Javascript to allow only alphanumeric

I need to find a reg ex that only allows alphanumeric. So far, everyone I try only works if the string is alphanumeric, meaning contains both a letter and a number. I just want one what would allow either and not require both.

Answers:

Answer
/^[a-z0-9]+$/i

^         Start of string
[a-z0-9]  a or b or c or ... z or 0 or 1 or ... 9
+         one or more times (change to * to allow empty string)
$         end of string    
/i        case-insensitive
Answer

If you wanted to return a replaced result, then this would work:

var a = 'Test123*** TEST';
var b = a.replace(/[^a-z0-9]/gi,'');
console.log(b);

This would return:

Test123TEST

Note that the gi is necessary because it means global (not just on the first match), and case-insensitive, which is why I have a-z instead of a-zA-Z. And the ^ inside the brackets means "anything not in these brackets".

WARNING: Alphanumeric is great if that's exactly what you want. But if you're using this in an international market on like a person's name or geographical area, then you need to account for unicode characters, which this won't do. For instance, if you have a name like "Âlvarö", it would make it "lvar".

Answer

Use the word character class. The following is equivalent to a ^[a-zA-Z0-9_]+$:

^\w+$

Explanation:

  • ^ start of string
  • \w any word character (A-Z, a-z, 0-9, _).
  • $ end of string

Use /[^\w]|_/g if you don't want to match the underscore.

Answer
/^([a-zA-Z0-9 _-]+)$/

the above regex allows spaces in side a string and restrict special characters.It Only allows a-z, A-Z, 0-9, Space, Underscore and dash.

Answer
^\s*([0-9a-zA-Z]*)\s*$

or, if you want a minimum of one character:

^\s*([0-9a-zA-Z]+)\s*$

Square brackets indicate a set of characters. ^ is start of input. $ is end of input (or newline, depending on your options). \s is whitespace.

The whitespace before and after is optional.

The parentheses are the grouping operator to allow you to extract the information you want.

EDIT: removed my erroneous use of the \w character set.

Answer

This will work

^(?=.*[a-zA-Z])(?=.*[0-9])[a-zA-Z0-9]+$

It accept only alphanumeriuc characters alone:
test cases pased :

dGgs1s23 - valid
12fUgdf  - valid,
121232   - invalid, 
abchfe   - invalid,
 abd()*  - invalid, 
42232^5$ - invalid

or

You can also try this one. this expression satisfied at least one number and one character and no other special characters

^(?=.*[0-9])(?=.*[a-zA-Z])([a-zA-Z0-9]+)$

in angular can test like:

$scope.str = '12fUgdf';
var pattern = new RegExp('^(?=.*[0-9])(?=.*[a-zA-Z])([a-zA-Z0-9]+)$');
$scope.testResult = pattern.test($scope.str);

PLUNKER DEMO

Refered:Regular expression for alphanumeric in Angularjs

Answer

Instead of checking for a valid alphanumeric string, you can achieve this indirectly by checking the string for any invalid characters. Do so by checking for anything that matches the complement of the valid alphanumeric string.

/[^a-z\d]/i    

Here is an example:

var alphanumeric = "someStringHere";
var myRegEx  = /[^a-z\d]/i;
var isValid = !(myRegEx.test(alphanumeric));

Notice the logical not operator at isValid, since I'm testing whether the string is false, not whether it's valid.

Answer

Extend the string prototype to use throughout your project

    String.prototype.alphaNumeric = function() {
        return this.replace(/[^a-z0-9]/gi,'');
    }

Usage:

    "I don't know what to say?".alphaNumeric();
    //Idontknowwhattosay
Answer

It seems like many users have noticed this these regular expressions will almost certainly fail unless we are strictly working in English. But I think there is an easy way forward that would not be so limited.

  1. make a copy of your string in all UPPERCASE
  2. make a second copy in all lowercase

Any characters that match in those strings are definitely not alphabetic in nature.

let copy1 = originalString.toUpperCase();
let copy2 = originalString.toLowerCase();
for(let i=0; i<originalString.length; i++) {
    let bIsAlphabetic = (copy1[i] != copy2[i]);
}

Optionally, you can also detect numerics by just looking for digits 0 to 9.

Answer

Try this... Replace you field ID with #name... a-z(a to z), A-Z(A to Z), 0-9(0 to 9)

jQuery(document).ready(function($){
    $('#name').keypress(function (e) {
        var regex = new RegExp("^[a-zA-Z0-9\s]+$");
        var str = String.fromCharCode(!e.charCode ? e.which : e.charCode);
        if (regex.test(str)) {
            return true;
        }
        e.preventDefault();
        return false;
    });
});
Answer

Input these code to your SCRATCHPAD and see the action.

var str=String("Blah-Blah1_2,oo0.01&zz%kick").replace(/[^\w-]/ig, '');
Answer

JAVASCRIPT to accept only NUMBERS, ALPHABETS and SPECIAL CHARECTERS

document.getElementById("onlynumbers").onkeypress = function (e) {
	onlyNumbers(e.key, e)
};

document.getElementById("onlyalpha").onkeypress = function (e) {
	onlyAlpha(e.key, e)
};

document.getElementById("speclchar").onkeypress = function (e) {
	speclChar(e.key, e)
};

function onlyNumbers(key, e) {
	var letters = /^[0-9]/g; //g means global
	if (!(key).match(letters)) e.preventDefault();
}

function onlyAlpha(key, e) {
	var letters = /^[a-z]/gi; //i means ignorecase
	if (!(key).match(letters)) e.preventDefault();
}

function speclChar(key, e) {
	var letters = /^[0-9a-z]/gi;
	if ((key).match(letters)) e.preventDefault();
}
<html>
   <head></head>
   <body>
      Enter Only Numbers: 
      <input id="onlynumbers" type="text">
      <br><br>
      Enter Only Alphabets: 
      <input id="onlyalpha" type="text" >
      <br><br>
      Enter other than Alphabets and numbers like special characters: 
      <input id="speclchar" type="text" >
   </body>
</html>

Answer

Even better than Gayan Dissanayake pointed out.

/^[-\w\s]+$/

Now ^[a-zA-Z0-9]+$ can be represented as ^\w+$

You may want to use \s instead of space. Note that \s takes care of whitespace and not only one space character.

Answer

I have string similar to Samsung Galaxy A10s 6.2-Inch (2GB,32GB ROM) Android 9.0, (13MP+2MP)+ 8MP Dual SIM 4000mAh 4G LTE Smartphone - Black (BF19)

Below is what i did:

string.replace(/[^a-zA-Z0-9 ,._-]/g, '').split(',').join('-').split(' ').join('-').toLowerCase()

Notice i allowed ,._- then use split() and join() to replace , to - and space to - respectively.

I ended up getting something like this: samsung-galaxy-a10s-6.2-inch-2gb-32gb-rom-android-9.0-13mp-2mp-8mp-dual-sim-4000mah-4g-lte-smartphone-black-bf19-20 which is what i wanted.

There might be a better solution but this is what i found working fine for me.

Answer

Jquery to accept only NUMBERS, ALPHABETS and SPECIAL CHARECTERS

<html>
<head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
</head>

<body>
Enter Only Numbers: 
<input type="text" id="onlynumbers">
<br><br>
Enter Only Alphabets: 
<input type="text" id="onlyalpha">
<br><br>
Enter other than Alphabets and numbers like special characters: 
<input type="text" id="speclchar">

<script>
    $('#onlynumbers').keypress(function(e) {
      var letters=/^[0-9]/g; //g means global
      if(!(e.key).match(letters)) e.preventDefault();
	});
    
    $('#onlyalpha').keypress(function(e) {
      var letters=/^[a-z]/gi; //i means ignorecase
      if(!(e.key).match(letters)) e.preventDefault();
	});
    
    $('#speclchar').keypress(function(e) {
      var letters=/^[0-9a-z]/gi; 
      if((e.key).match(letters)) e.preventDefault();
	});
    </script>
</body>
</html>

**JQUERY to accept only NUMBERS , ALPHABETS and SPECIAL CHARACTERS **


<!DOCTYPE html>
    $('#onlynumbers').keypress(function(e) {
      var letters=/^[0-9]/g; //g means global
      if(!(e.key).match(letters)) e.preventDefault();
    });

    $('#onlyalpha').keypress(function(e) {
      var letters=/^[a-z]/gi; //i means ignorecase
      if(!(e.key).match(letters)) e.preventDefault();
    });

    $('#speclchar').keypress(function(e) {
      var letters=/^[0-9a-z]/gi; 
      if((e.key).match(letters)) e.preventDefault();
    });
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"> 

Enter Only Numbers:

Enter Only Alphabets:

Enter other than Alphabets and numbers like special characters:

</body>
</html>
Answer

Save this constant

const letters = /^[a-zA-Z0-9]+$/

now, for checking part use .match()

const string = 'Hey there...' // get string from a keyup listner
let id = ''
// iterate through each letters
for (var i = 0; i < string.length; i++) {
  if (string[i].match(letters) ) {
    id += string[i]
  } else {
    // In case you want to replace with something else
    id += '-'  
  }
}
return id

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