https://sicc.cobaeh.edu.mx/LibreriaJS/Plugin/Externo/jLimitKeyPress/jLimitKeyPress.js

1/*
2composed by Brian Jaeger
3home page: brianjaeger.com
4*/
5(function ($) {
6  $.fn.limitkeypress = function (options) {
7    var defaults = {
8		rexp: /^[-+]?\d*\.?\d*$/ //only positive or negitive decimal numbers are allowed 
9	};
10	var options = $.extend(defaults, options);
11	
12	return this.each(function() {
13		var regExpression = options.rexp; //get the regular expression
14		
15		$(this).blur(function() { 
16			//this fixes the problem of paste of invalid data then loss of focus ie clicked submit button or tab 
17			sanitize(this);
18		});
19		
20		$(this).keypress(function(e) {
21			//allow backspace(8), enter(13), and other non character keypress events
22			if (e.which == "0" || e.which == "8" || e.which == "13" || e.ctrlKey || e.altKey){ 
23				return;
24			}
25			
26			//this fixes the problem of blur not triggering on enter keypress and it alows valid keypress events after an invalid paste/auto complete
27			sanitizeWithSelection(this); 
28			
29			var pressedChar = String.fromCharCode(e.which),  //get string value for pressed char
30				//insert the pressed char at the caret/cursor location for testing
31				updatedInput = this.value.substring(0, getSelectionStart(this))+pressedChar+this.value.substring(getSelectionEnd(this), this.value.length);
32			if (!regExpression.test(updatedInput)) {
33				e.preventDefault(); //stop the keypress event
34				return;
35			}
36			return;
37		});
38		
39		//steps throu each char  of a text input value validating each char + the next if the add is valid... 
40		function sanitizeWithSelection(o) {
41			var startCaretPos = getSelectionStart(o),
42				endCaretPos = getSelectionEnd(o),
43				temp = "",
44				testPlusChar = "",
45				selectionCharInfo = [];
46			
47			//records selection information for each char
48			for (i=0;i<o.value.length;i++) {
49				if (startCaretPos > i){
50					selectionCharInfo[i] = 'beforeSelection';
51				} else if ((startCaretPos <= i) && (endCaretPos > i)) {
52					selectionCharInfo[i] = 'inSelection';
53				} //note: if a char after the selection is invalid the selection would not change if that char is removed...
54			}
55			
56			for (i=0;i<o.value.length;i++) {
57				var iPlusOne = i + 1;
58				testPlusChar += o.value.substring(i,iPlusOne);
59				if ((!regExpression.test(testPlusChar))) {
60					var lastChar = testPlusChar.length-1;
61					temp = testPlusChar.substring(0,lastChar);
62					testPlusChar = temp;
63					if (selectionCharInfo[i] == 'beforeSelection'){
64						startCaretPos = startCaretPos - 1;
65						endCaretPos = endCaretPos - 1;
66					} else if (selectionCharInfo[i] == 'inSelection'){
67						endCaretPos = endCaretPos - 1;
68					}
69				}
70			}
71			o.value = testPlusChar;
72			setSelectionRange (o,startCaretPos,endCaretPos);
73		}
74		
75		//steps throu each char  of a text input value validating each char + the next if the add is valid... 
76		function sanitize(o) {
77			var temp = "",
78				testPlusChar = "";
79				
80			for (i=0;i<o.value.length;i++) {
81				var iPlusOne = i+1;
82				testPlusChar += o.value.substring(i,iPlusOne);
83				if ((!regExpression.test(testPlusChar))) {
84					var lastChar = testPlusChar.length-1;
85					temp = testPlusChar.substring(0,lastChar);
86					testPlusChar = temp;
87				}
88			}
89			o.value = testPlusChar;
90		}
91		
92		//from: http://javascript.nwbox.com/cursor_position/
93		function getSelectionStart(o) {
94			if (o.createTextRange) {
95				var r = document.selection.createRange().duplicate()
96				r.moveEnd('character', o.value.length)
97				if (r.text == '') return o.value.length
98				return o.value.lastIndexOf(r.text)
99			} else return o.selectionStart
100		}
101		
102		//from: http://javascript.nwbox.com/cursor_position/
103		function getSelectionEnd(o) {
104			if (o.createTextRange) {
105				var r = document.selection.createRange().duplicate()
106				r.moveStart('character', -o.value.length)
107				return r.text.length
108			} else return o.selectionEnd
109		}
110		
111		//from http://www.codingforums.com/archive/index.php/t-90176.html
112		function setSelectionRange(input, selectionStart, selectionEnd){
113			if (input.setSelectionRange) {
114				input.focus();
115				input.setSelectionRange(selectionStart, selectionEnd);
116			}
117			else if (input.createTextRange) {
118				var range = input.createTextRange();
119				range.collapse(true);
120				range.moveEnd('character', selectionEnd);
121				range.moveStart('character', selectionStart);
122				range.select();
123			}
124		}
125    });

126  };
127})(jQuery);