问题
i read many tutorials but i dont know how to do this, this is the input
input(type=\"text\",name=\"price\",id=\"price\"data-bind=\"text: price,valueUpdate:[\'afterkeydown\',\'propertychange\',\'input\']\")
and this is my viewModel
price: ko.computed(function()
{
return parseFloat(this.replace(\' \',\'\').replace(/[^0-9\\.]+/g,\"\")) || \'\';
},this)
but this cause error: this has no method replace??? how can i pass the price value to the computed function??
回答1:
Is better to create custom binding http://knockoutjs.com/documentation/custom-bindings.html which accept only allowed characters [0-9,.] as numeric representation.
put this line into your view
<input id="text" type="text" data-bind="numeric, value: number">
put this line into your model (remember to bind number as observable property)
ko.bindingHandlers.numeric = {
init: function (element, valueAccessor) {
$(element).on("keydown", function (event) {
// Allow: backspace, delete, tab, escape, and enter
if (event.keyCode == 46 || event.keyCode == 8 || event.keyCode == 9 || event.keyCode == 27 || event.keyCode == 13 ||
// Allow: Ctrl+A
(event.keyCode == 65 && event.ctrlKey === true) ||
// Allow: . ,
(event.keyCode == 188 || event.keyCode == 190 || event.keyCode == 110) ||
// Allow: home, end, left, right
(event.keyCode >= 35 && event.keyCode <= 39)) {
// let it happen, don't do anything
return;
}
else {
// Ensure that it is a number and stop the keypress
if (event.shiftKey || (event.keyCode < 48 || event.keyCode > 57) && (event.keyCode < 96 || event.keyCode > 105)) {
event.preventDefault();
}
}
});
}
};
回答2:
Knockout has extenders for this. Check This from knockoutjs.com explaining how to use observable extenders to force input to be numeric. I paste the code from the documentation here:
Source code: View
<p><input data-bind="value: myNumberOne" /> (round to whole number)</p>
<p><input data-bind="value: myNumberTwo" /> (round to two decimals)</p>
Source code: View model
ko.extenders.numeric = function(target, precision) {
//create a writable computed observable to intercept writes to our observable
var result = ko.pureComputed({
read: target, //always return the original observables value
write: function(newValue) {
var current = target(),
roundingMultiplier = Math.pow(10, precision),
newValueAsNum = isNaN(newValue) ? 0 : parseFloat(+newValue),
valueToWrite = Math.round(newValueAsNum * roundingMultiplier) / roundingMultiplier;
//only write if it changed
if (valueToWrite !== current) {
target(valueToWrite);
} else {
//if the rounded value is the same, but a different value was written, force a notification for the current field
if (newValue !== current) {
target.notifySubscribers(valueToWrite);
}
}
}
}).extend({ notify: 'always' });
//initialize with current value to make sure it is rounded appropriately
result(target());
//return the new computed observable
return result;
};
function AppViewModel(one, two) {
this.myNumberOne = ko.observable(one).extend({ numeric: 0 });
this.myNumberTwo = ko.observable(two).extend({ numeric: 2 });
}
ko.applyBindings(new AppViewModel(221.2234, 123.4525));
回答3:
I had a similar problem.
I also needed to ensure inter values only, and for IE9 and up (so type=numberical was not enough), and since we have a lot of international customers, i could not rely on keycodes either, so the following is what i ended up with:
//In my js class method (self is this as usual)
self.ensureNumberical = function (data, e) {
var keyValue = e.key;
if (keyValue.match(/[0-9]/g)) {
return true;
}
return false;
}
//In my MVC View
data-bind="event: { keypress: ensureNumberical }"
回答4:
An alternative approach: I have found that Knockout works well in combination with jQuery-validate. You just need to make sure that you validate the form before you attempt to use the numeric value.
Say you have a form DOM element, you can set up validation rules via
$(".yourform").validate({
rules: {
year: {
digits: true,
minlength: 4,
maxlength: 4
}
},
messages: {
year: "Please enter four digits (e.g. 2009).",
}
});
In your viewmodel you set the two-way binding up as usual, e.g. via self.year = ko.observable(""). Now make sure that you call $(".yourform").valid() before you are further processing self.year(). In my case, I am doing var year = parseInt(self.year(), 10). Right after form validation this is expected to always produce a meaningful result.
回答5:
Best for today's scenerio https://github.com/Knockout-Contrib/Knockout-Validation
run the snippet below. entering a non digit or something more than 255 will cause the message to display.
function model() {
var self = this;
this.myObj = ko.observable().extend({ digit: true }).extend({ max: 255});
}
var mymodel = new model();
$(document).ready(function() {
ko.validation.init();
ko.applyBindings(mymodel);
});<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout/3.2.0/knockout-min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/knockout-validation/2.0.3/knockout.validation.min.js"></script>
enter a digit less than or equal to 255 <input type="text" data-bind="textInput: myObj">
<p>
Enter something other than a digit or over 255 will cause an error.
</p>courtesy: Bryan Dellinger: https://stackoverflow.com/a/42940109/3868653
回答6:
<input type="text" id="alpha-validation" data-bind="value: YourDataName, valueUpdate: 'afterkeydown' , event: { 'input': AlphaCheck}" style="text-transform:uppercase">
create AlphaCheck Function and add that.
$('#alpha-validation').keyup(function () {
if (this.value.match(/[^0-9 ]/g)) {
this.value = this.value.replace(/[^0-9 ]/g, '');
}
});
That will works!
回答7:
I know this question is a year old but let me post this for the sake of feature visitor of the page.
Check this out:
ko.bindingHandlers.numericnumbers = {
init: function (element) {
$(element).on('keypress', function (number) {
number = (number) ? number : window.event;
var charcode = (number.which) ? number.which : number.keyCode;
if (charcode > 31 && (charcode < 48 || charcode > 75))
number.preventDefault();
});
}};
回答8:
Create you data-bind pointing at your shiny new code:
<input id="price" name="price" type="text" data-bind="numeric">
Shiny new knockout code:
price = ko.observable();
price.subscribe(function(newValue) {
price = newValue.replace(/[\D\.]/g, '');
});
This means that every time you update the price, it will apply the logic in the function (in this case stripping out anything that isn't a number or a period), and apply it directly to the price. You can also add other validation or cool features here, like adding a currency sybmol at the start, keeping it to 2 decimal places, etc...
回答9:
With the help of "keydown" event we can restrict other key's in text box which should hold numeric values.
$(document).ready(function(){
$("selector").on("keydown", function (e) {
//numbers, delete, backspace, arrows
var validKeyCodes = [8, 9, 37, 38, 39, 40, 46, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57];
if (!($.inArray(e.keyCode, validKeyCodes) >= 0))
e.preventDefault();
});
});
回答10:
We can restrict user to input user more than two decimal number Ex. 23.81, 3452.83 Modified code is as below. The reference code is taken from the @Martin Surynek answer.
HTML -
<p>
<input data-bind="value: myNumberOne" /> (round to whole number)</p>
<p>
<input data-bind="num, value: myNumberTwo" /> (round to two decimals)</p>
Script -
<script>
ko.bindingHandlers.num = {
init: function (element, valueAccessor) {
$(element).on("keypress", function (event) {
//debugger
console.log(event.keyCode);
var $this = $(this);
var text = $this.val();
// Stop insert two dots
if ($this.val().indexOf('.') != -1 && (event.which == 190 || event.which == 110)) {
event.preventDefault();
}
// Allow: backspace, delete, tab, escape, and enter
if (event.keyCode == 46 || event.keyCode == 8 || event.keyCode == 9 || event.keyCode == 27 || event.keyCode ==
13 ||
// Allow: Ctrl+A
(event.keyCode == 65 && event.ctrlKey === true) ||
// Allow: . ,event.keyCode == 188 ||
( event.keyCode == 190 || event.keyCode == 110) ||
// Allow: home, end, left, right
(event.keyCode >= 35 && event.keyCode <= 39)) {
// let it happen, don't do anything
return;
}
// Ensure that it is a number and stop the keypress
if (event.shiftKey || (event.keyCode < 48 || event.keyCode > 57) && (event.keyCode < 96 || event.keyCode >
105)) {
event.preventDefault();
}
if ((event.which == 46) && (text.indexOf('.') == -1)) {
setTimeout(function () {
if ($this.val().substring($this.val().indexOf('.')).length > 3) {
$this.val($this.val().substring(0, $this.val().indexOf('.') + 3));
}
}, 1);
}
if ((text.indexOf('.') != -1) &&
(text.substring(text.indexOf('.')).length > 2) &&
(event.which != 0 && event.which != 8) &&
($(this)[0].selectionStart >= text.length - 2)) {
event.preventDefault();
}
//console.log($(this)[0].selectionStart >= text.length - 2);
});
}
};
ko.extenders.numeric = function (target, precision) {
//create a writable computed observable to intercept writes to our observable
var result = ko.pureComputed({
read: target, //always return the original observables value
write: function (newValue) {
var current = target(),
roundingMultiplier = Math.pow(10, precision),
newValueAsNum = isNaN(newValue) ? 0 : parseFloat(+newValue),
valueToWrite = Math.round(newValueAsNum * roundingMultiplier) / roundingMultiplier;
//only write if it changed
if (valueToWrite !== current) {
target(valueToWrite);
} else {
//if the rounded value is the same, but a different value was written, force a notification for the current field
if (newValue !== current) {
target.notifySubscribers(valueToWrite);
}
}
}
}).extend({
notify: 'always'
});
//initialize with current value to make sure it is rounded appropriately
result(target());
//return the new computed observable
return result;
};
function AppViewModel(one, two) {
this.myNumberOne = ko.observable(one).extend({
numeric: 0
});
this.myNumberTwo = ko.observable(two).extend({
numeric: 2
});
}
ko.applyBindings(new AppViewModel(221.2234, 123.4525));
</script>
来源：https://stackoverflow.com/questions/17048468/make-an-input-only-numeric-type-on-knockout