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Regex - Numeric regex with . and ,

I have to create a regex that allows the user to input only a number (using . or ,)
so these examples are both valid:
8,5
8.5
here's my current code
private regex: RegExp = new RegExp(/^\d*[\,\.]{0,1}\d{1,2}/g);
However this allows me to input 8.,5 which is obviously bad. How can I change my regex so that the user can only place 1 of the decimal characters , OR .?
EDIT:
I've tried alot of answers, but most of them don't work (I can't place any decimal characters). Basically I'm creating a directive in angular that converts <input type="text"> to an numeric input (I can't use type="number")
Here's my directive code (see Angular2 - Input Field To Accept Only Numbers)
#Directive({
selector: "[OnlyNumber]"
})
export class OnlyNumberDirective {
// Allow decimal numbers. The \. is only allowed once to occur
private regex: RegExp = new RegExp(/^(?=.+)\d*(?:[\,\.]\d{1,2})?$/g);
// Allow key codes for special events. Reflect :
// Backspace, tab, end, home
private specialKeys: Array<string> = ["Backspace", "Tab", "End", "Home"];
constructor(private el: ElementRef) {
}
#HostListener("keydown", ["$event"])
onKeyDown(event: KeyboardEvent) {
// Allow Backspace, tab, end, and home keys
if (this.specialKeys.indexOf(event.key) !== -1) {
return;
}
let current: string = this.el.nativeElement.value;
let next: string = current.concat(event.key);
if (next && !String(next).match(this.regex)) {
event.preventDefault();
}
}
}
and here's how I use it in my template:
<mat-form-field class="numeric-textbox">
<input matInput
OnlyNumber
#model="ngModel"
placeholder="{{ label }}"
[ngModel]="selectedValue"/>
<mat-error><ng-content></ng-content></mat-error>
</mat-form-field>

You should specify the end of input string with $ without which a partial match will happen. You shouldn't look for \d* unless you want to match values like .5 or ,5 otherwise they will match as a valid input.
^\d+(?:[.,]\d{1,2})?$
Note: You don't need to escape dots or commas inside a character class and a quantifier like [.,]{0,1} is literally equal to [.,]?
Live demo:
document.getElementById("number").addEventListener("keyup",function(e) {
console.log(this.value.match(/^\d+(?:[.,]\d{1,2})?$/));
});
<input type="text" id="number" placeholder="Enter a number">
Update, based on comments
^(?![.,]?$)\d*[,.]?(?:\d{1,2})?$
This allows any number optionally followed or preceded by a decimal point or comma.
Live demo

The regex is correct, buy you just need to match the whole string:
^ start of the string
$ end of the string
However, the regex can be improved with:
^ : for start of string
\d+ : for at least 1 digit
(
[\,\.] : 1 comma
\d{1,2} : followed by 1 digit or two
)? : keep this optionnal. We can get numbers without commas
$ : end of string
Final regex may be:
/^\d+([\,\.]\d{1,2})?$/

Try: /^(?=.+)\d*(?:[,.]\d{1,2})?$/g
let regex = /^(?=.+)\d*(?:[,.]\d{1,2})?$/g,
strings = ["5", "50", "500", ".5", ",5","5.5","5,5", "5.55", "5,55", "5.555", "5,555", "5,,5", "5..5", "5,.5", "5.,5", "5,", "5."];
strings.forEach((string) => {
console.log(`${regex} ${string.match(regex) ? `matches ${string.match(regex)}`: `has no match for ${string}`}`);
});
This will match:
From the start, lookahead to make sure that there are characters present (one or more), and then begin matching: any amount of digits (0 or more), and the following optional: a comma or a dot, and then 1 or 2 digits before the end of the string.

Your regex is perfectly fine, you just need to specify the line's termination. You're currently matching 8 from 8,.5 which is likely why you're experiencing issues with your regex. I assume you're using JavaScript's test() function and getting true as a response for that string. Simply append $ to your regex and you'll get the correct answer. You can also simplify your regex to the following (also commented out in the snippet below). You can also probably drop the g flag as you're trying to match the string once, not multiple times:
^\d*[,.]?\d{1,2}$
What you're matching:
var a = ['8.5', '8,5', '.5', ',5', '8.,5']
var r = /^\d*[\,\.]{0,1}\d{1,2}/g
a.forEach(function(s){
console.log(s.match(r))
})
What you should be matching:
var a = ['8.5', '8,5', '.5', ',5', '8.,5']
var r = /^\d*[\,\.]{0,1}\d{1,2}$/g
// var r = /^\d*[,.]?\d{1,2}$/
a.forEach(function(s){
console.log(s.match(r))
})

Regex for alphanumeric with only one space or one hypen

I need a regular expression which needs to satisfy the following :-
It should accepts alphanumeric
only one space OR hyphen Or both can be there. But in any case it should be only one space or one hyphen
Max Total length should be 10 characters
For example valid data
W1A 1HQ
1234-456
IT-12345
12345
So far I have tried with below expression but it is not working properly
(^[a-zA-Z0-9][^\s\-].*[^\s\-][a-zA-Z0-9]){0,8}
Do I need to modify anything here ?
Edit
The solution posted here doesn't accept the combination of one space and one hypen within String.
Please provide an expression that will support all the requirement together in combinations.

You can use regex /^(?=.{0,10}$)[a-z0-9]+(?:[\s-][a-z0-9]+)?$/i
DEMO :
$('#input').on('input', function() {
$('#res').text(this.value.match(/^(?=.{0,10}$)[a-z0-9]+(?:[\s-][a-z0-9]+)?$/i) ? 'Valid' : 'Not Valid')
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<input id="input">
<div id="res"></div>
Explanation here
^(?=.{0,10}$)[a-z0-9]+(?:[\s-][a-z0-9]+)?$
UPDATE :
only one space OR hyphen Or both can be there
/^(?=.{0,10}$)[a-z0-9]+(?:([\s-])[a-z0-9]*(?:(?!\1)[\s-])?[a-z0-9]+)?$/i
$('#input').on('input', function() {
$('#res').text(this.value.match(/^(?=.{0,10}$)[a-z0-9]+(?:([\s-])[a-z0-9]*(?:(?!\1)[\s-])?[a-z0-9]+)?$/i) ? 'Valid' : 'Not Valid')
})
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<input id="input">
<div id="res"></div>
^(?=.{0,10}$)[a-z0-9]+(?:([\s-])[a-z0-9]*(?:(?!\1)[\s-])?[a-z0-9]+)?$

This expression also validates:
only one space OR hyphen Or both can be there
and allows hyphens/spaces at the beggining or end of the string.
Regex
/^(?!(?:[^-]*-){2}|(?:[^ ]* ){2})[- a-z0-9]{0,10}$/i
regex101 demo
It matches:
^ Start of string
(?!(?:[^-]*-){2}|(?:[^ ]* ){2}) Not followed by: (negative lookahead)
(?:[^-]*-){2}) 2 hyphens, or
(?:[^ ]* ){2} 2 spaces
[- a-z0-9]{0,10} alphanumerics, hyphens or spaces, with max length of 10
$ End of string
Mode /i: case insensitive match
Code
str = "-ABC 123";
re = /^(?!(?:[^-]*-){2}|(?:[^ ]* ){2})[- a-z0-9]{0,10}$/i;
if (str.match(re)) {
document.body.innerText += "VALID";
} else {
document.body.innerText += "Invalid string";
}

// Parameter: String which has to be checked with a
// regular Expression.
function checkString(toCheck) {
if (toCheck.length <= 10) {
var reg = /^[a-zA-Z0-9]+(\s|-|\s-|-\s)?[a-zA-Z0-9]+$/;
if (reg.test(toCheck)) {
return true;
}
}
return false;
}
Complete example on codepen:
http://codepen.io/mizech/pen/EVMRJG

Try this one:
^(?=.{1,10}$)([a-zA-Z0-9]+\s{0,1}[a-zA-Z0-9]*\-{0,1}[a-zA-Z0-9]+)$
Detailed explanation is available here: https://regex101.com/r/hV3rJ2/1

Javascript Regular Expression for numbers

I am trying to make a HTML form that accepts a rating through an input field from the user. The rating is to be a number from 0-10, and I want it to allow up to two decimal places. I am trying to use regular expression, with the following
function isRatingGood()
{
var rating = document.getElementById("rating").value;
var ratingpattern = new RegExp("^[0-9](\.[0-9][0-9]?)?$");
if(ratingpattern.test(rating))
{
alert("Rating Successfully Inputted");
return true;
}
else
{
return rating === "10" || rating === "10.0" || rating === "10.00";
}
}
However, when I enter any 4 or 3 digit number into the field, it still works. It outputs the alert, so I know it is the regular expression that is failing. 5 digit numbers do not work. I used this previous answer as a basis, but it is not working properly for me.
My current understanding is that the beginning of the expression should be a digit, then optionally, a decimal place followed by 1 or 2 digits should be accepted.

You are using a string literal to created the regex. Inside a string literal, \ is the escape character. The string literal
"^[0-9](\.[0-9][0-9]?)?$"
produces the value (and regex):
^[0-9](.[0-9][0-9]?)?$
(you can verify that by entering the string literal in your browser's console)
\. is not valid escape sequence in a string literal, hence the backslash is ignored. Here is similar example:
> "foo\:bar"
"foo:bar"
So you can see above, the . is not escaped in the regex, hence it keeps its special meaning and matches any character. Either escape the backslash in the string literal to create a literal \:
> "^[0-9](\\.[0-9][0-9]?)?$"
"^[0-9](\.[0-9][0-9]?)?$"
or use a regex literal:
/^[0-9](\.[0-9][0-9]?)?$/

The regular expression you're using will parsed to
/^[0-9](.[0-9][0-9]?)?$/
Here . will match any character except newline.
To make it match the . literal, you need to add an extra \ for escaping the \.
var ratingpattern = new RegExp("^[0-9](\\.[0-9][0-9]?)?$");
Or, you can simply use
var ratingPattern = /^[0-9](\.[0-9][0-9]?)?$/;
You can also use \d instead of the class [0-9].
var ratingPattern = /^\d(\.\d{1,2})?$/;
Demo
var ratingpattern = new RegExp("^[0-9](\\.[0-9][0-9]?)?$");
function isRatingGood() {
var rating = document.getElementById("rating").value;
if (ratingpattern.test(rating)) {
alert("Rating Successfully Inputted");
return true;
} else {
return rating === "10" || rating === "10.0" || rating === "10.00";
}
}
<input type="text" id="rating" />
<button onclick="isRatingGood()">Check</button>

Below find a regex candidate for your task:
^[0-1]?\d(\.\d{0,2})?$
Demo with explanation
var list = ['03.003', '05.05', '9.01', '10', '10.05', '100', '1', '2.', '2.12'];
var regex = /^[0-1]?\d(\.\d{0,2})?$/;
for (var index in list) {
var str = list[index];
var match = regex.test(str);
console.log(str + ' : ' + match);
}

This should also do the job. You don't need to escape dots from inside the square brackets:
^((10|\d{1})|\d{1}[.]\d{1,2})$
Also if you want have max rating 10 use
10| ---- accept 10
\d{1})| ---- accept whole numbers from 0-9 replace \d with [1-9]{1} if don't want 0 in this
\d{1}[.]\d{1,2} ---- accept number with two or one numbers after the coma from 0 to 9
LIVE DEMO: https://regex101.com/r/hY5tG4/7
Any character except ^-]\ All characters except the listed special characters are literal characters that add themselves to the character class. [abc] matches a, b or c literal characters

Just answered this myself.
Need to add square brackets to the decimal point, so the regular expression looks like
var ratingpattern = new RegExp("^[0-9]([\.][0-9][0-9]?)?$");

Replace matching elements in array using regular expressions: invalid character

var input = [paul, Paula, george];
var newReg = \paula?\i
for(var text in input) {
if (newReg.test(text) == true) {
input[input.indexOf(text)] = george
}
}
console.log(input)
I don't know what's wrong in my code. it should change paul and Paula to george but when I run it it says there's an illegal character

The backslash (\) is an escape character in Javascript (along with a lot of other C-like languages). This means that when Javascript encounters a backslash, it tries to escape the following character. For instance, \n is a newline character (rather than a backslash followed by the letter n).
So, thats what is causing your error, you need to replace \paula?\i with /paula?/i

You need to replace \ by / in your regexp pattern.
You should wrap the strings inside quotes "
You need to match correctly your array, val is just the index of the word, not the word himself.
var input = ["paul", "Paula", "george"];
var newReg = /paula?/i;
for (var val in input) {
if (newReg.test(input[val]) == true) {
input[input.indexOf(input[val])] = "george";
}
}
console.log(input);
JSFIDDLE

Validating Phone Number With RegExp Not Working

I have a function which validates the phone number entered by the user using regexp. However it does not seem to evaluate true even though the regexp is correct. I am not sure what i am doing incorrectly.
Html
<body class="claro">
<form id="myform" data-dojo-type="dijit/form/Form">
<input
data-dojo-type="dijit/form/ValidationTextBox"
data-dojo-props="
required: true,
invalidMessage: 'Invalid Phone Number !',
missingMessage: 'Phone Number Required !'"
id="phone" title="Phone Number"
placeholder="Your Phone Number"
onkeydown="validatePhoneNumberFormat()"/>
</form>
</body>
Javascript
//test phone number 188-123-1234
function validatePhoneNumberFormat(){
var phoneNumber = dijit.byId("phone");
var phoneFormat = new RegExp('^[0-9]\d{2}-\d{3}-\d{4}$');
phoneNumber.validator = function(value){
console.log(value);
console.log(phoneFormat.test(value.trim()));
return phoneFormat.test(value.trim());
}
}

You need to double escape \d inside RegExp constructor, so use this:
var phoneFormat = new RegExp('^\\d{3}-\\d{3}-\\d{4}$');
Or else use regex literal:
var phoneFormat = /^\d{3}-\d{3}-\d{4}$/;
Since RegExp takes a string as an argument you need to double escape all the special meta characters as one escape is used for String and second is for regex engine.

This will work:
function validatePhoneNumberFormat(){
var phoneNumber = dijit.byId("phone");
var phoneFormat = /^\d{3}-\d{3}-\d{4}$/;
phoneNumber.validator = function(value){
console.log(value);
console.log(phoneFormat.test(value.trim()));
return phoneFormat.test(value.trim());
}
}
REGEX EXPLANATION
/^\d{3}-\d{3}-\d{4}$/
Assert position at the beginning of the string «^»
Match a single character that is a “digit” (ASCII 0–9 only) «\d{3}»
Exactly 3 times «{3}»
Match the character “-” literally «-»
Match a single character that is a “digit” (ASCII 0–9 only) «\d{3}»
Exactly 3 times «{3}»
Match the character “-” literally «-»
Match a single character that is a “digit” (ASCII 0–9 only) «\d{4}»
Exactly 4 times «{4}»
Assert position at the very end of the string «$»