In your action method, return Json(object) to return JSON to your page.
public ActionResult SomeActionMethod() {
return Json(new {foo="bar", baz="Blech"});
}
Then just call the action method using Ajax. You could use one of the helper methods from the ViewPage such as
<%= Ajax.ActionLink("SomeActionMethod", new AjaxOptions {OnSuccess="somemethod"}) %>
SomeMethod would be a javascript method that then evaluates the Json object returned.
If you want to return a plain string, you can just use the ContentResult:
public ActionResult SomeActionMethod() {
return Content("hello world!");
}
ContentResult by default returns a text/plain as its contentType.
This is overloadable so you can also do:
return Content("<xml>This is poorly formatted xml.</xml>", "text/xml");
Note: This is an updated answer. Comments below refer to an old version which messed around with keycodes.
jQuery
Try it yourself on JSFiddle.
There is no native jQuery implementation for this, but you can filter the input values of a text <input>
with the following inputFilter
plugin (supports Copy+Paste, Drag+Drop, keyboard shortcuts, context menu operations, non-typeable keys, the caret position, different keyboard layouts, and all browsers since IE 9):
// Restricts input for the set of matched elements to the given inputFilter function.
(function($) {
$.fn.inputFilter = function(inputFilter) {
return this.on("input keydown keyup mousedown mouseup select contextmenu drop", function() {
if (inputFilter(this.value)) {
this.oldValue = this.value;
this.oldSelectionStart = this.selectionStart;
this.oldSelectionEnd = this.selectionEnd;
} else if (this.hasOwnProperty("oldValue")) {
this.value = this.oldValue;
this.setSelectionRange(this.oldSelectionStart, this.oldSelectionEnd);
} else {
this.value = "";
}
});
};
}(jQuery));
You can now use the inputFilter
plugin to install an input filter:
$(document).ready(function() {
$("#myTextBox").inputFilter(function(value) {
return /^\d*$/.test(value); // Allow digits only, using a RegExp
});
});
See the JSFiddle demo for more input filter examples. Also note that you still must do server side validation!
Pure JavaScript (without jQuery)
jQuery isn't actually needed for this, you can do the same thing with pure JavaScript as well. See this answer.
HTML 5
HTML 5 has a native solution with <input type="number">
(see the specification), but note that browser support varies:
- Most browsers will only validate the input when submitting the form, and not when typing.
- Most mobile browsers don't support the
step
, min
and max
attributes.
- Chrome (version 71.0.3578.98) still allows the user to enter the characters
e
and E
into the field. Also see this question.
- Firefox (version 64.0) and Edge (EdgeHTML version 17.17134) still allow the user to enter any text into the field.
Try it yourself on w3schools.com.
Best Answer
There is another way to do it, too, without having to create your own extension.
Say for instance we have the following in one of our controllers:
We can then do the following in our view:
The will prevent the error message of
'<b>Please Use a Valid Person Name</b>'
from being encoded.