https://www.ontona.com/javascripts/jquery.maxlength_1415077697.js

1/*
2  @author: remy sharp / http://remysharp.com
3  @params:
4    feedback - the selector for the element that gives the user feedback. Note that this will be relative to the form the plugin is run against.
5    hardLimit - whether to stop the user being able to keep adding characters. Defaults to true.
6    useInput - whether to look for a hidden input named 'maxlength' instead of the maxlength attribute. Defaults to false.
7    words - limit by characters or words, set this to true to limit by words. Defaults to false.
8  @license: Creative Commons License - ShareAlike http://creativecommons.org/licenses/by-sa/3.0/
9  @version: 1.2
10  @changes: code tidy via Ariel Flesler and fix when pasting over limit and including \t or \n
11*/
12
13(function ($) {
14
15$.fn.maxlength = function (settings) {
16
17    if (typeof settings == 'string') {
18        settings = { feedback : settings };
19    }
20
21    settings = $.extend({}, $.fn.maxlength.defaults, settings);
22
23    function length(el) {
24    	var parts = el.value;
25    	if ( settings.words )
26    		parts = el.value.length ? parts.split(/\s+/) : { length : 0 };
27    	return parts.length;
28    }
29    
30    return this.each(function () {
31        var field = this,
32        	$field = $(field),
33        	$form = $(field.form),
34        	limit = settings.useInput ? $form.find('input[name=maxlength]').val() : $field.attr('maxlength'),
35        	$charsLeft = $form.find(settings.feedback);
36
37    	function limitCheck(event) {
38        	var len = length(this),
39        	    exceeded = len >= limit,
40        		code = event.keyCode;
41
42        	if ( !exceeded )
43        		return;
44
45            switch (code) {
46                case 8:  // allow delete
47                case 9:
48                case 17:
49                case 36: // and cursor keys
50                case 35:
51                case 37: 
52                case 38:
53                case 39:
54                case 40:
55                case 46:
56                case 65:
57                    return;
58
59                default:
60                    return settings.words && code != 32 && code != 13 && len == limit;
61            }
62        }
63
64
65        var updateCount = function () {
66            var len = length(field),
67            	diff = limit - len;
68
69            $charsLeft.html( diff || "0" );
70
71            // truncation code
72            if (settings.hardLimit && diff < 0) {
73            	field.value = settings.words ? 
74            	    // split by white space, capturing it in the result, then glue them back
75            		field.value.split(/(\s+)/, (limit*2)-1).join('') :
76            		field.value.substr(0, limit);
77
78                updateCount();
79            }
80        };
81
82        $field.keyup(updateCount).change(updateCount);
83        if (settings.hardLimit) {
84            $field.keydown(limitCheck);
85        }
86
87        updateCount();
88    });
89};
90
91$.fn.maxlength.defaults = {
92    useInput : false,
93    hardLimit : true,
94    feedback : '.charsLeft',
95    words : false
96};
97
98})(jQuery);