How to limit the number of characters entered in a text area

Here's my attempt at limiting the number of characters entered into a text area:

var limit = 255;
var txt = $('textarea[id$=txtPurpose]');

$(txt).keyup(function() {
    var len = $(this).val().length;
    if (len > limit) {
        //this.value = this.value.substring(0, 50);
        $(this).addClass('goRed');
        $('#spn').text(len - limit + " characters exceeded");
        return false;
    } else {
        $(this).removeClass('goRed');
        $('#spn').text(limit - len + " characters left");
    }
});

H开发者_开发技巧owever, it doesn't work very well. How can I prevent a user from entering text once a certain limit has been reached, say 255 characters?

Though this question is pretty old. If I was you I do something very simple like

<textarea maxlength="255"></textarea>

This would limit the users to enter only 255 characters in the textarea.

Here's what I use to limit something to 1200 chars. When someone types too many characters, I just truncate the contents of that textarea.

$(function() {
    //set up text length counter
    $('#id_limited_textarea').keyup(function() {
        update_chars_left(1200, $('#id_limited_textarea')[0], $('#text_chars_left'));
    });
    //and fire it on doc ready, too
    update_chars_left(1200, $('#id_limited_textarea')[0], $('#text_chars_left'));

});

function update_chars_left(max_len, target_input, display_element) {
   var text_len = target_input.value.length;
   if (text_len >= max_len) {
       target_input.value = target_input.value.substring(0, max_len); // truncate
       display_element.html("0");
   } else {
       display_element.html(max_len - text_len);
   }
}

$(this).val( $(this).val().substring(0, limit) );

To simplify this to the bare bone basic:

<textarea name="message" onkeydown="return this.value.substr(0,160)"></textarea>

Set your max to where 160 is.

My plugin:

(function($) {

   $.fn.textCounter = function(options) {

        var defaults = {
            maxlimit: 100,      // max limit character
            description: null,  // element for descript count character
            enter: true         // if accept enter
        };

        var options = $.extend({}, defaults, options);

        if (options.description != null) {
            if (typeof options.description == 'string')
                options.description = $('#' + options.description);
        }

        var fevent = function(ev) {

            var value = $(this).val(),
                k = ev.charCode || ev.keyCode || ev.which,
                incremente = 1;

            if (k == 8)
                incremente = -1;

            if (options.enter == false && k == 13)
                return false;

            if (ev.ctrlKey || ev.altKey || ev.metaKey)  //Ignore
                return true;

            if ((value.length + incremente) > options.maxlimit)
                return false;

            return true;
        };

        var fcounter = function(ev) {
            var value = $(this).val();
            $(options.description).text(options.maxlimit - value.length);
        };

        $(this).each(function(i, el) {
            if ($(this).is(':input')) {
                $(this).unbind('keypress.textCounter').bind('keypress.textCounter', fevent);
                $(this).unbind('keyup.textCounter').bind('keyup.textCounter', fcounter);
            }
        });

    };

})(jQuery);

var limit="NO of characters";<br><br>
$(this).val( $(this).val().substring(0, limit) );