Following on from another question I asked, i really didnt seem to be getting anywhere. Due to my ineptitude. I chose the guys answer because , well he answered my question.

I am gathering I didnt ask the right question cos I have no idea what to do ..

So issue is I have input element . Keeping it simple;

<input type="text" maxlength="12" name="price" id="price" class="foo">

I want users to be able to type in numbers only and only one period ( . ) anywhere in that price. so could be 3.00 or 300.00 or 3000

Could someone please help me out, I am going goggle eyed.

The Older question asked was here Quick regex with alert

Following on from another question I asked, i really didnt seem to be getting anywhere. Due to my ineptitude. I chose the guys answer because , well he answered my question.

I am gathering I didnt ask the right question cos I have no idea what to do ..

So issue is I have input element . Keeping it simple;

<input type="text" maxlength="12" name="price" id="price" class="foo">

I want users to be able to type in numbers only and only one period ( . ) anywhere in that price. so could be 3.00 or 300.00 or 3000

Could someone please help me out, I am going goggle eyed.

The Older question asked was here Quick regex with alert

• javascript
• html
• forms

• what about 300.? Is that a valid input? – Anurag Commented Jan 20, 2012 at 2:20
• @Anurag yes thats fine. we can strip out the . if nothing follows it server side – 422 Commented Jan 20, 2012 at 2:25
• is just a . an acceptable input? – Anurag Commented Jan 20, 2012 at 2:28
• @Anurag no. I was thinking, that regex ( not that I understand it or how to implement it ) could be set to expect a number ( min 1 number ) then any combination of either other numbers or one period. – 422 Commented Jan 20, 2012 at 2:34
• Can it be a number like 123.45 or does the part after a decimal (if one exists) have to be all zeros? – j08691 Commented Jan 20, 2012 at 2:44

3 Answers 3

You could, in the change event of the input, check if the number format is OK. This code will try to get the number and remove anything else: (I'm assuming you use jQuery, if not, please do)

$('#price').change(function() {
    $(this).val($(this).val().match(/\d*\.?\d+/));
});

See it working here.

EDIT: if you don't have jQuery, this code does the same (at least in Chrome):

document.getElementById('price').onchange = function() {
    this.value = this.value.match(/\d*\.?\d+/);
};

EDIT 2: not sure if I follow, but you could add this too to prevent letters and other characters before the change event:

$('#price').keypress(function(event) {
    var code = (event.keyCode ? event.keyCode : event.which);
    if (!(
            (code >= 48 && code <= 57) //numbers
            || (code == 46) //period
        )
        || (code == 46 && $(this).val().indexOf('.') != -1)
       )
        event.preventDefault();
});

Here is my solution(It also validates data/values copy&pasted):

function InputValidator(input, validationType, validChars) {
if (input === null || input.nodeType !== 1 || input.type !== 'text' && input.type !== 'number')
    throw ('Please specify a valid input');

if (!(InputValidator.ValidationType.hasOwnProperty(validationType) || validationType))
    throw 'Please specify a valid Validation type';

input.InputValidator = this;

input.InputValidator.ValidCodes = [];

input.InputValidator.ValidCodes.Add = function (item) {
    this[this.length] = item;
};

input.InputValidator.ValidCodes.hasValue = function (value, target) {
    var i;
    for (i = 0; i < this.length; i++) {
        if (typeof (target) === 'undefined') {
            if (this[i] === value)
                return true;
        }
        else {
            if (this[i][target] === value)
                return true;
        }
    }

    return false;
};

var commandKeys = {
    'backspace': 8,
    'tab': 9,
    'enter': 13,
    'shift': 16,
    'ctrl': 17,
    'alt': 18,
    'pause/break': 19,
    'caps lock': 20,
    'escape': 27,
    'page up': 33,
    'page down': 34,
    'end': 35,
    'home': 36,
    'left arrow': 37,
    'up arrow': 38,
    'right arrow': 39,
    'down arrow': 40,
    'insert': 45,
    'delete': 46,
    'left window key': 91,
    'right window key': 92,
    'select key': 93,
    /*creates Confusion in IE */
    //'f1': 112,
    //'f2': 113,
    //'f3': 114,
    //'f4': 115,
    //'f5': 116,
    //'f6': 117,
    //'f7': 118,
    //'f8': 119,
    //'f9': 120,
    //'f10': 121,
    //'f11': 122,
    //'f12': 123,
    'num lock': 144,
    'scroll lock': 145,
};

commandKeys.hasValue = function (value) {
    for (var a in this) {
        if (this[a] === value)
            return true;
    }

    return false;
};

function getCharCodes(arrTarget, chars) {
    for (var i = 0; i < chars.length; i++) {
        arrTarget.Add(chars[i].charCodeAt(0));
    }
}

function triggerEvent(name, element) {
    if (document.createEventObject) {
        // dispatch for IE
        var evt = document.createEventObject();
        return element.fireEvent('on' + name, evt)
    }
    else {
        // dispatch for firefox + others
        var evt = document.createEvent("HTMLEvents");
        evt.initEvent(name, true, true); // event type,bubbling,cancelable
        return !element.dispatchEvent(evt);
    }
}

if (validationType == InputValidator.ValidationType.Custom) {
    if (typeof (validChars) === 'undefined')
        throw 'Please add valid characters';

    getCharCodes(input.InputValidator.ValidCodes, validChars);
}
else if (validationType == InputValidator.ValidationType.Decimal) {
    getCharCodes(input.InputValidator.ValidCodes, '0123456789.');
}
else if (validationType == InputValidator.ValidationType.Numeric) {
    getCharCodes(input.InputValidator.ValidCodes, '0123456789');
}

input.InputValidator.ValidateChar = function (c) {
    return this.ValidCodes.hasValue(c.charCodeAt(0));
}

input.InputValidator.ValidateString = function (s) {
    var arr = s.split('');

    for (var i = 0; i < arr.length; i++) {
        if (!this.ValidateChar(arr[i])) {
            arr[i] = '';
        }
    }

    return arr.join('');
}

function bindEvent(el, eventName, eventHandler) {
    if (el.addEventListener) {
        el.addEventListener(eventName, eventHandler, false);
    } else if (el.attachEvent) {
        el.attachEvent('on' + eventName, eventHandler);
    }
}

function getCaretPosition(i) {
    if (!i) return;

    if ('selectionStart' in i) {
        return i.selectionStart;
    }
    else {
        if (document.selection) {
            var sel = document.selection.createRange();
            var selLen = document.selection.createRange().text.length;
            sel.moveStart('character', -i.value.length);
            return sel.text.length - selLen;
        }
    }
}

function setCursor(node, pos) {
    var node = (typeof (node) === "string" || node instanceof String) ? document.getElementById(node) : node;

    if (!node) {
        return false;
    }
    else if (node.createTextRange) {
        var textRange = node.createTextRange();
        textRange.collapse(true);
        textRange.moveEnd(pos);
        textRange.moveStart(pos);
        textRange.select();
        return true;
    } else if (node.setSelectionRange) {
        node.setSelectionRange(pos, pos);
        return true;
    }

    return false;
}

function validateActive() {
    if (input.isActive) {
        var pos = getCaretPosition(input);

        var arr = input.value.split('');

        for (var i = 0; i < arr.length; i++) {
            if (!this.ValidateChar(arr[i])) {
                arr[i] = '';

                if (pos > i)
                    pos--;
            }
        }
        console.log('before : ' + input.value);

        input.value = arr.join('');
        console.log('after : ' + input.value, input);
        setCursor(input, pos);

        setTimeout(validateActive, 10);
    }
}

bindEvent(input, 'keypress', function (e) {
    var evt = e || window.event;
    var charCode = evt.which || evt.keyCode;

    if (!input.InputValidator.ValidCodes.hasValue(charCode) && !commandKeys.hasValue(charCode)) {
        if (evt.preventDefault) {
            evt.preventDefault();
            evt.stopPropagation();
        }
        return false;
    }
});

bindEvent(input, 'keyup', function (e) {
    var evt = e || window.event;
    var charCode = evt.which || evt.keyCode;

    if (!input.InputValidator.ValidCodes.hasValue(charCode) && !commandKeys.hasValue(charCode)) {
        if (evt.preventDefault) {
            evt.preventDefault();
            evt.stopPropagation();
        }
        return false;
    }
});

bindEvent(input, 'change', function (e) {
    var dt = input.value;

    input.value = input.InputValidator.ValidateString(input.value);

    if (input.value !== dt)
        triggerEvent('change', input);
});

bindEvent(input, 'blur', function (e) {
    var dt = input.value;
    input.value = input.InputValidator.ValidateString(input.value);

    input.isActive = false;

    if (input.value !== dt)
        triggerEvent('blur', input);
});

bindEvent(input, 'paste', function (e) {
    var evt = e || window.event;
    var svt = input.value;

    if (evt && evt.clipboardData && evt.clipboardData.getData) {// Webkit - get data from clipboard, put into editdiv, cleanup, then cancel event
        if (/text\/html/.test(evt.clipboardData.types)) {
            var dt = evt.clipboardData.getData('text/html');

            input.value = input.InputValidator.ValidateString(dt);
            if (input.value !== dt)
                triggerEvent('change', input);
        }
        else if (/text\/plain/.test(e.clipboardData.types)) {
            var dt = evt.clipboardData.getData('text/plain');

            input.value = input.InputValidator.ValidateString(dt);
            if (input.value !== dt)
                triggerEvent('change', input);
        }
        else {
            input.value = '';
        }
        waitforpastedata(input, svt);
        if (e.preventDefault) {
            e.stopPropagation();
            e.preventDefault();
        }
        return false;
    }
    else {// Everything else - empty editdiv and allow browser to paste content into it, then cleanup
        input.value = '';
        waitforpastedata(input, svt);
        return true;
    }
});

bindEvent(input, 'select', function (e) {
    var evt = e || window.event;

    if (evt.preventDefault) {
        evt.preventDefault();
        evt.stopPropagation();
    }
    return false;
});

bindEvent(input, 'selectstart', function (e) {
    var evt = e || window.event;

    if (evt.preventDefault) {
        evt.preventDefault();
        evt.stopPropagation();
    }
    return false;
});

/* no need to validate wile active,
   removing F keys fixed IE compatability*/
//bindEvent(input, 'fucus', function (e) {
//    input.isActive = true;
//    validateActive();
//});

//validate current value of the textbox
{
    var dt = input.value;
    input.value = input.InputValidator.ValidateString(input.value);

    //trigger event to indicate value has changed
    if (input.value !== dt)
        triggerEvent('change', input);
}

function waitforpastedata(elem, savedcontent) {
    if (elem.value !== '') {
        var dt = input.value;
        elem.value = elem.InputValidator.ValidateString(elem.value);

        if (input.value !== dt)
            triggerEvent('change', input);
    }
    else {
        var that = {
            e: elem,
            s: savedcontent
        }
        that.callself = function () {
            waitforpastedata(that.e, that.s)
        }
        setTimeout(that.callself, 10);
    }
}
}

InputValidator.ValidationType = new (function (types) {
    for (var i = 0; i < types.length; i++) {
        this[types[i]] = types[i];
    }
})(['Numeric', 'Custom', 'Decimal']);

To apply it to an input, do the following :

new InputValidator(document.getElementById('txtValidate'), InputValidator.ValidationType.Decimal);/* Numeric or Custom */

If you specify Custom as the validation type you have to specify the valid characters. eg :

new InputValidator(document.getElementById('txtValidate'), InputValidator.ValidationType.Custom,'1234abc');

Cambraca aproach kind of works, but the best one is the last mentioned approach , you cancel the keypress event filtering the keys before it shows up instead of undoing what was already done. A consequence of changing the value after the fact is that it may affect the position of the caret in the field.

Here's an example of abstracting the idea in a cross-browser way. Somebody should port this to a jQuery plugin http://www.qodo.co.uk/assets/files/javascript-restrict-keyboard-character-input.html

Ok, I guess I'll port it. But I'm not a jQuery guy so this is an untested bare bones jQuery plugin that uses their code http://jsfiddle.net/mendesjuan/VNSU7/3

(function( $ ) {
    $.fn.restrict = function(regExp, additionalRestriction) {
        function restrictCharacters(myfield, e, restrictionType) {
            var code = e.which;
            var character = String.fromCharCode(code);
            // if they pressed esc... remove focus from field...
            if (code==27) { this.blur(); return false; }
            // ignore if they are press other keys
            // strange because code: 39 is the down key AND ' key...
            // and DEL also equals .
            if (!e.originalEvent.ctrlKey && code!=9 && code!=8 && code!=36 && code!=37 && code!=38 && (code!=39 || (code==39 && character=="'")) && code!=40) {
                if (character.match(restrictionType)) {
                    return additionalRestriction(myfield.value, character);
                } else {
                    return false;
                }
            }
        }
        this.keypress(function(e){
            if (!restrictCharacters(this, e, regExp)) {
                e.preventDefault();
            }
        });
    };
})( jQuery );

$('#field').restrict(/[0-9\.]/g, function (currentValue, newChar) {
    return !(currentValue.indexOf('.') != -1 && newChar == ".");    
});