Develop Reference

Regexp to capture comma separated values

I have a string that can be a comma separated list of \w, such as:
abc123
abc123,def456,ghi789
I am trying to find a JavaScript regexp that will return ['abc123'] (first case) or ['abc123', 'def456', 'ghi789'] (without the comma).
I tried:
^(\w+,?)+$ -- Nope, as only the last repeating pattern will be matched, 789
^(?:(\w+),?)+$ -- Same story. I am using non-capturing bracket. However, the capturing just doesn't seem to happen for the repeated word
Is what I am trying to do even possible with regexp? I tried pretty much every combination of grouping, using capturing and non-capturing brackets, and still not managed to get this happening...

If you want to discard the whole input when there is something wrong, the simplest way is to validate, then split:
if (/^\w+(,\w+)*$/.test(input)) {
var values = input.split(',');
// Process the values here
}
If you want to allow empty value, change \w+ to \w*.
Trying to match and validate at the same time with single regex requires emulation of \G feature, which assert the position of the last match. Why is \G required? Since it prevents the engine from retrying the match at the next position and bypass your validation. Remember than ECMA Script regex doesn't have look-behind, so you can't differentiate between the position of an invalid character and the character(s) after it:
something,=bad,orisit,cor&rupt
^^ ^^
When you can't differentiate between the 2 positions, you can't rely on the engine to do a match-all operation alone. While it is possible to use a while loop with RegExp.exec and assert the position of last match yourself, why would you do so when there is a cleaner option?
If you want to savage whatever available, torazaburo's answer is a viable option.

Live demo
Try this regex :
'/([^,]+)/'
Alternatively, strings in javascript have a split method that can split a string based on a delimeter:
s.split(',')

Split on the comma first, then filter out results that do not match:
str.split(',').filter(function(s) { return /^\w+$/.test(s); })

This regex pattern separates numerical value in new line which contains special character such as .,,,# and so on.
var val = [1234,1213.1212, 1.3, 1.4]
var re = /[0-9]*[0-9]/gi;

var str = "abc123,def456, asda12, 1a2ass, yy8,ghi789";
var re = /[a-z]{3}\d{3}/g;
var list = str.match(re);
document.write("<BR> list.length: " + list.length);
for(var i=0; i < list.length; i++) {
document.write("<BR>list(" + i + "): " + list[i]);
}
This will get only "abc123" code style in the list and nothing else.

May be you can use split function
var st = "abc123,def456,ghi789";
var res = st.split(',');

how to validate a text field in jsp using java script for accepting only dot and comma as special characters

I need to allow only numerics, dot and comma in a text field. If the user enters other special characters an alert needs to be thrown.
Please find below the conditions:
The text field should contain atleast one numeric value.
It is not mandatory that the text field should contain dot and comma always.
Thanks for your help.

Here is a start for you: http://jsfiddle.net/KLyy8/1/
Unless you tell us the exact specifics we won't know how to write the regular expression. Sounds like you want numbers with thousands separator and decimals. But how many of each? The fiddle above will work for numbers like this...
123,456.79
12,345.6
1,234.56
etc...
validate=function(){
var str = document.getElementById('test').value;
var patt = new RegExp("^[0-9]{1,3}\,[0-9]{3}\.[0-9]{1,2}$");
var res = patt.test(str);
alert(res);
}

If the field should contain only numeric values with decimal places (for exmaple 3.14, 112358 or 9,81), then you can use only one regex:
function validateString(str){
if(str.match(^[0-9\.,]+$)){
return true;
}else{
return false;
}
However if you want to be precise you will probably want to limit the dots and commas to one, if I understand your situation correctly.
Regex for that can look like this
^[0-9]+(\.|,){0,1}[0-9]+$
That means it starts with a number (^[0-9]+), then it may contain zero or one times one comma or dot ((\.|,){0,1}) and then again ends with a number ([0-9]+$).

Javascript string validation using the regex object

I am complete novice at regex and Javascript. I have the following problem: need to check into a textfield the existence of one (1) or many (n) consecutive * (asterisk) character/characters eg. * or ** or *** or infinite (n) *. Strings allowed eg. *tomato or tomato* or **tomato or tomato** or as many(n)*tomato many(n)*. So, far I had tried the following:
var str = 'a string'
var value = encodeURIComponent(str);
var reg = /([^\s]\*)|(\*[^\s])/;
if (reg.test(value) == true ) {
alert ('Watch out your asterisks!!!')
}

By your question it's hard to decipher what you're after... But let me try:
Only allow asterisks at beginning or at end
If you only allow an arbitrary number (at least one) of asterisks either at the beginning or at the end (but not on both sides) like:
*****tomato
tomato******
but not **tomato*****
Then use this regular expression:
reg = /^(?:\*+[^*]+|[^*]+\*+)$/;
Match front and back number of asterisks
If you require that the number of asterisks at the biginning matches number of asterisks at the end like
*****tomato*****
*tomato*
but not **tomato*****
then use this regular expression:
reg = /^(\*+)[^*]+\1$/;
Results?
It's unclear from your question what the results should be when each of these regular expressions match? Are strings that test positive to above regular expressions fine or wrong is on you and your requirements. As long as you have correct regular expressions you're good to go and provide the functionality you require.
I've also written my regular expressions to just exclude asterisks within the string. If you also need to reject spaces or anything else simply adjust the [^...] parts of above expressions.
Note: both regular expressions are untested but should get you started to build the one you actually need and require in your code.

If I understand correctly you're looking for a pattern like this:
var pattern = /\**[^\s*]+\**/;
this won't match strings like ***** or ** ***, but will match ***d*** *d or all of your examples that you say are valid (***tomatos etc).If I misunderstood, let me know and I'll see what I can do to help. PS: we all started out as newbies at some point, nothing to be ashamed of, let alone apologize for :)
After the edit to your question I gather the use of an asterisk is required, either at the beginning or end of the input, but the string must also contain at least 1 other character, so I propose the following solution:
var pattern = /^\*+[^\s*]+|[^\s*]+\*+$/;
'****'.match(pattern);//false
' ***tomato**'.match(pattern);//true
If, however *tomato* is not allowed, you'll have to change the regex to:
var pattern = /^\*+[^\s*]+$|^[^\s*]+\*+$/;
Here's a handy site to help you find your way in the magical world of regular expressions.

getting contents of string between digits

have a regex problem :(
what i would like to do is to find out the contents between two or more numbers.
var string = "90+*-+80-+/*70"
im trying to edit the symbols in between so it only shows up the last symbol and not the ones before it. so trying to get the above variable to be turned into 90+80*70. although this is just an example i have no idea how to do this. the length of the numbers, how many "sets" of numbers and the length of the symbols in between could be anything.
many thanks,
Steve,

The trick is in matching '90+-+' and '80-+/' seperately, and selecting only the number and the last constant.
The expression for finding the a number followed by 1 or more non-numbers would be
\d+[^\d]+
To select the number and the last non-number, add parens:
(\d+)[^\d]*([^\d])
Finally add a /g to repeat the procedure for each match, and replace it with the 2 matched groups for each match:
js> '90+*-+80-+/*70'.replace(/(\d+)[^\d]*([^\d])/g, '$1$2');
90+80*70
js>

Or you can use lookahead assertion and simply remove all non-numerical characters which are not last: "90+*-+80-+/*70".replace(/[^0-9]+(?=[^0-9])/g,'');

You can use a regular expression to match the non-digits and a callback function to process the match and decide what to replace:
var test = "90+*-+80-+/*70";
var out = test.replace(/[^\d]+/g, function(str) {
return(str.substr(-1));
})
alert(out);
See it work here: http://jsfiddle.net/jfriend00/Tncya/
This works by using a regular expression to match sequences of non-digits and then replacing that sequence of non-digits with the last character in the matched sequence.

i would use this tutorial, first, then review this for javascript-specific regex questions.

This should do it -
var string = "90+*-+80-+/*70"
var result = '';
var arr = string.split(/(\d+)/)
for (i = 0; i < arr.length; i++) {
if (!isNaN(arr[i])) result = result + arr[i];
else result = result + arr[i].slice(arr[i].length - 1, arr[i].length);
}
alert(result);
Working demo - http://jsfiddle.net/ipr101/SA2pR/

Similar to #Arnout Engelen
var string = "90+*-+80-+/*70";
string = string.replace(/(\d+)[^\d]*([^\d])(?=\d+)/g, '$1$2');
This was my first thinking of how the RegEx should perform, it also looks ahead to make sure the non-digit pattern is followed by another digit, which is what the question asked for (between two numbers)
Similar to #jfriend00
var string = "90+*-+80-+/*70";
string = string.replace( /(\d+?)([^\d]+?)(?=\d+)/g
, function(){
return arguments[1] + arguments[2].substr(-1);
});
Instead of only matching on non-digits, it matches on non-digits between two numbers, which is what the question asked
Why would this be any better?
If your equation was embedded in a paragraph or string of text. Like:
This is a test where I want to clean up something like 90+*-+80-+/*70 and don't want to scrap the whole paragraph.
Result (Expected) :
This is a test where I want to clean up something like 90+80*70 and don't want to scrap the whole paragraph.
Why would this not be any better?
There is more pattern matching, which makes it theoretically slower (negligible)
It would fail if your paragraph had embedded numbers. Like:
This is a paragraph where Sally bought 4 eggs from the supermarket, but only 3 of them made it back in one piece.
Result (Unexpected):
This is a paragraph where Sally bought 4 3 of them made it back in one piece.

Regex for validation

Can anyone tell me how to write a regex for the following scenario. The input should only be numbers or - (hyphen) or , (comma). The input can be given as any of the following
23
23,26
1-23
1-23,24
24,25-56,58-40,45
Also when numbers is given in a range, the second number should be greater than the first one. 23-1 should not be allowed. If a number is already entered it should not be allowed again. Like 1-23,23 should not be allowed

I'm not going to quibble with "I think" or "maybe" -- you can not do this with a Regex.
Matching against a regex can validate that the form of the input is correct, and can also be used to extract pieces of the input, but it can not do value comparisons, or duplicate elimination (except in limited well defined circumstances), or range checking.
What you have as input I interpret as a comma-separated list of values or ranges of values; in BNFish notation:
value :: number
range :: value '-' value
term :: value | range
list :: term [','term]*
A regex can be built that will match this to verify correct structure, but you'll have to do other validation for the value comparisons and to prevent the duplicate numbers.
The most straigtforward regex I can think of (on short notice) is this
([0-9]+|[0-9]+-[0-9]+)(, *([0-9]+|[0-9]+-[0-9]+))*
You have digits or digits-digits, optionally followed by comma[optional space](digits or digits-digits) - repeated zero or more times.
I tested this regex at http://www.fileformat.info/tool/regex.htm with the input 3,4-12,6,2,90-221
Of course you can replace the [0-9] with [\d] for regex dialects that allow it.

var str = "24,25-56,24, 58- 40,a 45",
trimmed = str.replace(/\s+/g, '')
//test for correct characters
if (trimmed.match(/[^,\-\d]/)) alert("Please use only digits and hyphens, separated by commas.")
//test for duplicates
var split = trimmed.split(/-|,/)
split.sort()
for (var i = 0; i < split.length - 1; i++) {
if (split[i + 1] == split[i]) alert("Please avoid duplicate numbers.")
}
//test for ascending range
split = trimmed.split(/,/)
for (var i in split) {
if (split[i].match("-") && eval(split[i]) < 0) alert("Please use an ascending range.")
}

I don't think you will be able to do this with a RegEx. Especially not the part about set logic - number already used, valid sequential range.
My suggestion would be to have a Regex verify the format, at the least -, number, comma. Then use the split method on commas and loop over the input to verify the set. Something like:
var number_ranges = numbers.split(',');
for (var i = 0; i < number_ranges.length; ++i) {
// verify number ranges in set
}
That logic is not exactly trivial.

I think with regular expressions it is better to take the time to learn them than to throw someone elses script into yours without knowing exactly what it is doing. You have excellent resources out there to help you.
Try these sites:
regular-expressions.info
w3schools.com
evolt.org
Those are the first three results form a google search. All are good resources. Good luck. Remember to double check what your regex is actually matching by outputing it to the screen, don't assume you know (that has bitten me more than one time).