问题
I found the following JQuery function here which prevents a user from entering anything that's not a number or a single decimal. The function works well but I'd like to improve it to prevent the user from entering 3 or more decimal places i.e. disallow 99.999 and allow 99.99. Any ideas?
function checkForInvalidCharacters(event, inputBox){
if ((event.which != 46 || inputBox.val().indexOf('.') != -1) && (event.which < 48 || event.which > 57)) {
event.preventDefault();
}
};
回答1:
The logic is every time a user entering a number you have to check two things.
- Has the user entered decimal point?
- Are the decimal places more than two?
For the first one you can use $(this).val().indexOf('.') != -1
For the second one you can use $(this).val().substring($(this).val().indexOf('.'), $(this).val().indexOf('.').length).length > 2
EDIT-1
Also, you have to add event.which != 0 && event.which != 8 so that arrow keys and backspace work in Firefox (Manoj comment)
EDIT-2
Also, you have to add $(this)[0].selectionStart >= text.length - 2 so that you can add digits if the cursor is to the left of the decimal point (BIdesi comment)
EDIT-3
Also, you have to check if user deleted . and placed it somewhere else creating a value with more than 2 digits after the decimal. So you have to add
$this.val($this.val().substring(0, $this.val().indexOf('.') + 3)); for cutting extra digits (Gilberto Sánchez comment)
EDIT-4
To handle pasted data, you must bind a paste event handler.Then you have to check if pasted data have . withtext.indexOf('.') > -1 and more than 2 digits after the decimal with text.substring(text.indexOf('.')).length > 3. If so, you have to cut extra digits. Also you have to check that user entered numeric input with $.isNumeric() (darasd comment).
Here is the code:
$('.number').keypress(function(event) {
var $this = $(this);
if ((event.which != 46 || $this.val().indexOf('.') != -1) &&
((event.which < 48 || event.which > 57) &&
(event.which != 0 && event.which != 8))) {
event.preventDefault();
}
var text = $(this).val();
if ((event.which == 46) && (text.indexOf('.') == -1)) {
setTimeout(function() {
if ($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();
}
});
$('.number').bind("paste", function(e) {
var text = e.originalEvent.clipboardData.getData('Text');
if ($.isNumeric(text)) {
if ((text.substring(text.indexOf('.')).length > 3) && (text.indexOf('.') > -1)) {
e.preventDefault();
$(this).val(text.substring(0, text.indexOf('.') + 3));
}
}
else {
e.preventDefault();
}
});.number {
padding: 5px 10px;
font-size: 16px;
}<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" class="number" />回答2:
I've updated the function for a few extra cases.
- It will allow negative numbers
- It will allow you to edit the left of the decimal when there are already 2 digits to the right
- It allows you to use the arrow keys and backspace when you are in Firefox
- It also handles pasted data
/**
* Given an input field, this function will only allow numbers with up to two decimal places to be input.
* @param {object} element
* @return {number}
*/
function forceNumber(element) {
element
.data("oldValue", '')
.bind("paste", function(e) {
var validNumber = /^[-]?\d+(\.\d{1,2})?$/;
element.data('oldValue', element.val())
setTimeout(function() {
if (!validNumber.test(element.val()))
element.val(element.data('oldValue'));
}, 0);
});
element
.keypress(function(event) {
var text = $(this).val();
if ((event.which != 46 || text.indexOf('.') != -1) && //if the keypress is not a . or there is already a decimal point
((event.which < 48 || event.which > 57) && //and you try to enter something that isn't a number
(event.which != 45 || (element[0].selectionStart != 0 || text.indexOf('-') != -1)) && //and the keypress is not a -, or the cursor is not at the beginning, or there is already a -
(event.which != 0 && event.which != 8))) { //and the keypress is not a backspace or arrow key (in FF)
event.preventDefault(); //cancel the keypress
}
if ((text.indexOf('.') != -1) && (text.substring(text.indexOf('.')).length > 2) && //if there is a decimal point, and there are more than two digits after the decimal point
((element[0].selectionStart - element[0].selectionEnd) == 0) && //and no part of the input is selected
(element[0].selectionStart >= element.val().length - 2) && //and the cursor is to the right of the decimal point
(event.which != 45 || (element[0].selectionStart != 0 || text.indexOf('-') != -1)) && //and the keypress is not a -, or the cursor is not at the beginning, or there is already a -
(event.which != 0 && event.which != 8)) { //and the keypress is not a backspace or arrow key (in FF)
event.preventDefault(); //cancel the keypress
}
});
}
forceNumber($("#myInput"));<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" id="myInput" />回答3:
It can also be done with a regular expression:
$('.class').on('input', function () {
this.value = this.value.match(/^\d+\.?\d{0,2}/);
});
Name the css selector .class to whatever you like and put it on the input.
回答4:
thank you! I have added the possibility of deleting the numbers and '.' once typed:
The event.keyCode !== 8 does that action for backspace.
The event.keyCode !== 46 does that action for delete.
$( document ).ready(function() {
$('#Ds_Merchant_Amount').keypress(function(event) {
if ((event.which != 46 || $(this).val().indexOf('.') != -1) && (event.which < 48 || event.which > 57) ) {
if (event.keyCode !== 8 && event.keyCode !== 46 ){ //exception
event.preventDefault();
}
}
if(($(this).val().indexOf('.') != -1) && ($(this).val().substring($(this).val().indexOf('.'),$(this).val().indexOf('.').length).length>2 )){
if (event.keyCode !== 8 && event.keyCode !== 46 ){ //exception
event.preventDefault();
}
}
});
});
回答5:
Numeric values With Decimal Point up to 2 decimal point validation. Dependency jQuery.
HTML -
<span>Float</span>
<input type="text" name="numeric" class='allownumericwithdecimal'>
<div>Numeric values only allowed (With Decimal Point) </div>
JQuery Code -
Method 1-
$(".allownumericwithdecimal").on("keypress keyup blur", function (event) {
var patt = new RegExp(/[0-9]*[.]{1}[0-9]{2}/i);
var matchedString = $(this).val().match(patt);
if (matchedString) {
$(this).val(matchedString);
}
if ((event.which != 46 || $(this).val().indexOf('.') != -1) && (event.which < 48 || event.which > 57)) {
event.preventDefault();
}
});
Method 2 -
$(".allownumericwithdecimal").on("keypress keyup blur", function (event) {
var patt = new RegExp(/(?<=\.\d\d).+/i);
$(this).val($(this).val().replace(patt, ''));
if ((event.which != 46 || $(this).val().indexOf('.') != -1) && (event.which < 48 || event.which > 57)) {
event.preventDefault();
}
});
回答6:
I have updated this routine to allow standard editing features as these were prevented in the above code. (This routine is just for processing a float but can be adapted to allow only 2 digits after the decimal)
var value = $(this).val().toString();
// Allowed Keys
if (event.which === 8 || event.which === 46 // Character delete
|| event.which === 16 || event.which === 17 // Modifier Key
|| event.which === 37 || event.which === 39 // Arrow Keys
|| (event.key.toLowerCase() === "a" && event.ctrlKey) // Select All
|| (event.key.toLowerCase() === "c" && event.ctrlKey) // Copy
|| (event.key.toLowerCase() === "x" && event.ctrlKey) // Cut
|| (event.key.toLowerCase() === "v" && event.ctrlKey) // Paste
|| (event.which === 45 && event.ctrlKey) // Old school copy (CTRL + INSERT)
|| (event.which === 46 && event.shiftKey) // Old school cut (SHIFT + DELETE)
|| (event.which === 45 && event.shiftKey) // Old school paste (SHIFT + INSERT)
|| (event.which === 35) // END
|| (event.which === 36) // HOME
|| (event.which === 35 && event.shiftKey) // SHIFT + END
|| (event.which === 36 && event.shiftKey) // SHIFT + HOME
)
{
return;
}
else if (event.which === 190) // Process decimal point
{
if (value == "" || value.indexOf(".") > -1)
{
event.preventDefault();
}
}
else if (event.which < 48 || event.which > 57 || event.ctrlKey || event.shiftKey) // Reject anything else that isn't a number
{
event.preventDefault();
}
回答7:
Try this
HTML
<input type="text" id="min_rent" name="min_rent" onkeypress="return isPrice(event,$('#min_rent').val())">
Jquery
function isPrice(evt,value) {
var charCode = (evt.which) ? evt.which : event.keyCode;
if((value.indexOf('.')!=-1) && (charCode != 45 && (charCode < 48 || charCode > 57)))
return false;
else if(charCode != 45 && (charCode != 46 || $(this).val().indexOf('.') != -1) && (charCode < 48 || charCode > 57))
return false;
return true;
}
Worked Link demo
来源：https://stackoverflow.com/questions/21796827/jquery-allow-only-two-numbers-after-decimal-point