Given an input element and the task is to check whether the input element is alphanumeric or not. There are two methods to solve this problem which are discussed below:
Approach 1:
- A RegExp is used to validate the input.
- RegExp is used to check the string of invalid characters which doesn’t contain (a-z) alphabets and all numeric digits to validate.
- A not operator is used for desired output.
Example 1: This example implements the above approach.
<!DOCTYPE HTML> <html>
<head>
<title>
How to validate an input is alphanumeric
or not using JavaScript?
</title>
</head>
<body align = "center">
<h1 style = "color:green;" >
GeeksForGeeks
</h1>
<p id = "GFG_UP" style =
"font-size: 15px; font-weight: bold;">
</p>
<form id = "formElement">
Input: <input id = "input1" type = "text" />
</form>
<br>
<button onclick = "GFG_Fun()">
click here
</button>
<p id = "GFG_DOWN" style =
"font-size: 24px; font-weight: bold; color:green;">
</p>
<script>
var el_up = document.getElementById('GFG_UP');
var el_down = document.getElementById('GFG_DOWN');
var input = document.getElementById('input1');
el_up.innerHTML = "Click on the button to "
+ "validate alphanumeric input.";
function GFG_Fun() {
var val = input.value;
var RegEx = /[^a-z\d]/i;
var Valid = !(RegEx.test(val));
el_down.innerHTML = Valid;
}
</script>
</body>
</html>
|
Output:
-
Before clicking on the button:
-
After clicking on the button:
Approach 2:
- A different RegExp is used to validate the input.
- RegExp is checking for the (a-z) alphabets and (0-9) digits to validate.
Example 2: This example implements the above approach.
<!DOCTYPE HTML> <html>
<head>
<title>
JavaScript | Validate If input is alphanumeric or not?
</title>
</head>
<body id = "body" align = "center">
<h1 style = "color:green;" >
GeeksForGeeks
</h1>
<p id = "GFG_UP" style =
"font-size: 15px; font-weight: bold;">
</p>
<form id = "formElement">
Input: <input id = "input1" type = "text" />
</form>
<br>
<button onclick = "GFG_Fun()">
click here
</button>
<p id = "GFG_DOWN" style =
"font-size: 24px; font-weight: bold; color:green;">
</p>
<script>
var el_up = document.getElementById('GFG_UP');
var el_down = document.getElementById('GFG_DOWN');
var input = document.getElementById('input1');
el_up.innerHTML = "Click on the button to "
+ "validate alphanumeric input.";
function GFG_Fun() {
var val = input.value;
var RegEx = /^[a-z0-9]+$/i;
var Valid = RegEx.test(val);
el_down.innerHTML = Valid;
}
</script>
</body>
</html>
|
Output:
-
Before clicking on the button:
-
After clicking on the button:
Article Tags :
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