Limit Character Input including Copy paste in Textarea using JavaScript

You can use the maxlength attribute within an input element like textarea or a textbox, to limit the character input, including copy paste. It is also possible using jQuery or you can use plain old JavaScript. Here in this post, I’ll show you how using a JavaScript code, you can limit character input in a Textarea element and also show a character counter.

Limit character input in textarea element using JavaScript

1) Using maxlength attribute

The maxlength attribute specifies the maximum number of characters allowed in an input element like the <textarea>. For example,


<textarea id="tArea" cols="50" maxlength="20"></textarea>

Try it

This is simple. It also prevents entering characters more than the specified number even if you copy and paste some value in the input box. You don’t need a script to do this. I have tested it using many browsers, including IE 10. It worked nicely.

Or, use a textbox with the attribute like this.

<input id="txt" type="text" maxlength="20" placeholder="Enter some value">

However, you’ll have to elaborate the "placeholder" value like, "Enter some value (max. 20 chars limit)" etc., to make it very specific so that the user who is typing in knows the character limit. Or, you can add a <label> element to specify the character limit.

2) Using JavaScript to Limit Character input

We can make the process a little more dynamic, like showing a character counter using a JavaScript code. That is, we can limit the character input, at the same time show a counter, like number of characters remaining, while entering values in the <textarea> element.

<!doctype html>
<html>
<body>
    <h3>
        Enter some characters in the box. (Max. 20 chars limit)
    </h3>
    
    <div>
        <textarea id="tArea" cols="50" 
            oninput="limitChar(this)" maxlength="20"></textarea>

        <p id="charCounter">20 Characters limit</p>
    </div>
</body>

<script>
    let limitChar = (element) => {
        const maxChar = 20;
        
        let ele = document.getElementById(element.id);
        let charLen = ele.value.length;
        
        let p = document.getElementById('charCounter');
        p.innerHTML = maxChar - charLen + ' characters remaining';
        
        if (charLen > maxChar) 
        {
            ele.value = ele.value.substring(0, maxChar);
            p.innerHTML = 0 + ' characters remaining'; 
        }
    }

// THIS SCRIPT WILL WORK IN IE 10.

//  function limitChar(element)
//  {
//      var maxChar = 20;
        
//      var ele = document.getElementById(element.id);
//      var charLen = ele.value.length;
        
//      var p = document.getElementById('charCounter');
//      p.innerHTML = maxChar - charLen + ' characters remaining';
        
//      if (charLen > maxChar) 
//      {
//          ele.value = ele.value.substring(0, maxChar);
//          p.innerHTML = 0 + ' characters remaining'; 
//      }    	
//  }
</script>
</html>

Try it

There’s nothing much to explain. The character limit is specified in a variable or a constant. The length of the text in a <textarea> is compared with the constant value 20.

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