I have this regex
var mregex = /(\$m[\w|\.]+)/g;
string mstring= "$m.x = $m.y";
So basically capture each instance of $m.[+ any number of alphanumeric or . until another character or the end]
I have this working in C# but I'm trying to port it over to javascript, so dropped the name capture.
var match = mregexp.exec(mstring);
match has
0: "$m.x"
1: "$m.x" // not $m.y as I would have expected.
What am i doing wrong?
thanks
You regular expression just matches once. The [0] element of the return array is the entire matched substring. The [1] element is the first group, which in your case is the same. You'd have to call .exec() again to get it to find the second instance.
You can pass a function to .replace(), which I personally like:
mstring.replace(mregexp, function(_, group) {
console.log( group );
});
That'd show you both matched groups. (The function is passed arguments that are of the same nature as the elements of the returned array from .exec().)
You will have to repeat mregexp.exec() until it returns null.
var match = []; //initialize a new array
while(mregexp.exec(mstring)){
match.push(mregexp[1]);
}
For Javascript's flavor of regexen see http://www.regular-expressions.info/javascript.html
You can call mstring.match(mregexp) to return all of the matches, but you only see the matched substrings (in which case you could simplify mregexp to /\$m[\w.]+/g).
Related
In my web page, I have:
var res = number.match(/[0-9\+\-\(\)\s]+/g);
alert(res);
As you can see, I want to get only numbers, the characters +, -, (, ) and the space(\s)
When I tried number = '98+66-97fffg9', the expected result is: 98+66-979
but I get 98+66-97,9
the comma is an odd character here! How can eliminate it?
Its probably because you get two groups that satisfied your expression.
In other words: match mechanism stops aggregating group when it finds first unwanted character -f. Then it skips matching until next proper group that, in this case, contains only one number - 9. This two groups are separated by comma.
Try this:
var number = '98+66-97fffg9';
var res = number.match(/[0-9\+\-\(\)\s]+/g);
// res is an array! You have to join elements!
var joined = res.join('');
alert(joined);
You're getting this because your regex matched two results in the number string, not one. Try printing res, you'll see that you've matched both 98+66-979 as well as 9
String.match returns an array of matched items. In your case you have received two items ['98+66-97','9'], but alert function outputs them as one string '98+66-97,9'. Instead of match function use String.replace function to remove(filter) all unallowable characters from input number:
var number = '98+66-97fffg9',
res = number.replace(/[^0-9\+\-\(\)\s]+/g, "");
console.log(res); // 98+66-979
stringvariable.match(/[0-9\+\-\(\)\s]+/g); will give you output of matching strings from stringvariable excluding unmatching characters.
In your case your string is 98+66-97fffg9 so as per the regular expression it will eliminate "fffg" and will give you array of ["98+66-97","9"].
Its default behavior of match function.
You can simply do res.join('') to get the required output.
Hope it helps you
As per documents from docs, the return value is
An Array containing the entire match result and any parentheses-captured matched results, or null if there were no matches.
S,your return value contains
["98+66-97", "9"]
So if you want to skip parentheses-captured matched results
just remove g flag from regular expression.
So,your expression should like this one
number.match(/[0-9\+\-\(\)\s]+/); which gives result ["98+66-97"]
I am trying to fetch the value after equal sign, its works but i am getting duplicated values , any idea whats wrong here?
// Regex for finding a word after "=" sign
var myregexpNew = /=(\S*)/g;
// Regex for finding a word before "=" sign
var mytype = /(\S*)=/g;
//Setting data from Grid Column
var strNew = "QCById=20";
var matchNew = myregexpNew.exec(strNew);
var newtype = mytype.exec(strNew);
alert(matchNew);
https://jsfiddle.net/6vjjv0hv/
exec returns an array, the first element is the global match, the following ones are the submatches, that's why you get ["=20", "20"] (using console.log here instead of alert would make it clearer what you get).
When looking for submatches and using exec, you're usually interested in the elements starting at index 1.
Regarding the whole parsing, it's obvious there are better solution, like using only one regex with two submatches, but it depends on the real goal.
You can try without using Regex like this:
var val = 'QCById=20';
var myString = val.substr(val.indexOf("=") + 1);
alert(myString);
Presently exec is returning you the matched value.
REGEXP.exec(SOMETHING) returns an array (see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/exec).
The first item in the array is the full match and the rest matches the parenthesized substrings.
You do not get duplicated values, you just get an array of a matched value and the captured text #1.
See RegExp#exec() help:
If the match succeeds, the exec() method returns an array and updates properties of the regular expression object. The returned array has the matched text as the first item, and then one item for each capturing parenthesis that matched containing the text that was captured.
Just use the [1] index to get the captured text only.
var myregexpNew = /=(\S*)/g;
var strNew = "QCById=20";
var matchNew = myregexpNew.exec(strNew);
if (matchNew) {
console.log(matchNew[1]);
}
To get values on both sides of =, you can use /(\S*)=(\S*)/g regex:
var myregexpNew = /(\S*)=(\S*)/g;
var strNew = "QCById=20";
var matchNew = myregexpNew.exec(strNew);
if (matchNew) {
console.log(matchNew[1]);
console.log(matchNew[2]);
}
Also, you may want to add a check to see if the captured values are not undefined/empty since \S* may capture an empty string. OR use /(\S+)=(\S+)/g regex that requires at least one non-whitespace character to appear before and after the = sign.
For instance one has the simple regular expression:
var regex = /([^\\^\{^\}]+)|(\\[A-Za-z]+(\{[^}^{]*})*)|($[.]+$)|($$[.]+$$)/g;
and a string to check:
var text = '\\a{b}{c}{d}';
on witch the function var matched = regex.exec(text) is runned.
The returned Array machted looks now like:
matched =['\\a{b}{c}{d}', undefined, '\\a{b}{c}{d}', '{d}', undefined, undefined];
What do the single entries mean? And how to control them?
Thanks in advance!
var regex = /([^\\^\{^\}]+)|(\\[A-Za-z]+(\{[^}^{]*})*)|($[.]+$)|($$[.]+$$)/;
regex.exec('\\a{b}{c}{d}');
//=> ["\a{b}{c}{d}", undefined, "\a{b}{c}{d}", "{d}", undefined, undefined]
Resulting array contains matched groups where first element of array is whole input that matched your regex.
undefined means some of your groups didn't match anything and remained empty.
You can use **non-capturing groups and avoid undefined:
var regex = /(?:[^\\^\{^}]+)|(\\[A-Za-z]+(\{[^}^{]*})*)|(?:$[.]+$)|(?:$$[.]+$$)/;
regex.exec('\\a{b}{c}{d}');
//=> ["\a{b}{c}{d}", "\a{b}{c}{d}", "{d}"]
This is just how RegExp.prototype.exec works.
The groups in your regex — contents inside the () chars — create elements in the returned array
The zero-th element is the full match substring, the following elements are the substrings that were matched by capture groups (....). For a simpler example:
/(c)|(b(.))./.exec('abcdef') should return ['bcd', undefined, 'bc', 'c']. The pattern is an alternation between (c) and (b(.)).; "bcd" came before "c", so the second alternative matched while the first didn't. Thus, first capture group (c) is undefined, since it matched nothing. The second capture group (b(.)) matched "bc". The third, (.), matched "c".
Let's start with a simplier example :
var text = 'azrt12345';
var regex = /([a-z]+)|([0-9]+)/;
var matched = regex.exec(text);
/* matched = ["azrt", "azrt", undefined] */
As you can see, the regexp catches an alpha string or a numeric one. As text begins with alpha characters, the first capturing group works, not the second. Then, matched[0] contains the whole string matched, matched[1] the first capturing group (with what it captured), matched[2] the second one (with nothing captured, then it contains undefined).
See this excellent doc to understand the way it works.
So currently, my code works for inputs that contain one set of parentheses.
var re = /^.*\((.*\)).*$/;
var inPar = userIn.replace(re, '$1');
...meaning when the user enters the chemical formula Cu(NO3)2, alerting inPar returns NO3) , which I want.
However, if Cu(NO3)2(CO2)3 is the input, only CO2) is being returned.
I'm not too knowledgable in RegEx, so why is this happening, and is there a way I could put NO3) and CO2) into an array after they are found?
You want to use String.match instead of String.replace. You'll also want your regex to match multiple strings in parentheses, so you can't have ^ (start of string) and $ (end of string). And we can't be greedy when matching inside the parentheses, so we'll use .*?
Stepping through the changes, we get:
// Use Match
"Cu(NO3)2(CO2)3".match(/^.*\((.*\)).*$/);
["Cu(NO3)2(CO2)3", "CO2)"]
// Lets stop including the ) in our match
"Cu(NO3)2(CO2)3".match(/^.*\((.*)\).*$/);
["Cu(NO3)2(CO2)3", "CO2"]
// Instead of matching the entire string, lets search for just what we want
"Cu(NO3)2(CO2)3".match(/\((.*)\)/);
["(NO3)2(CO2)", "NO3)2(CO2"]
// Oops, we're being a bit too greedy, and capturing everything in a single match
"Cu(NO3)2(CO2)3".match(/\((.*?)\)/);
["(NO3)", "NO3"]
// Looks like we're only searching for a single result. Lets add the Global flag
"Cu(NO3)2(CO2)3".match(/\((.*?)\)/g);
["(NO3)", "(CO2)"]
// Global captures the entire match, and ignore our capture groups, so lets remove them
"Cu(NO3)2(CO2)3".match(/\(.*?\)/g);
["(NO3)", "(CO2)"]
// Now to remove the parentheses. We can use Array.prototype.map for that!
var elements = "Cu(NO3)2(CO2)3".match(/\(.*?\)/g);
elements = elements.map(function(match) { return match.slice(1, -1); })
["NO3", "CO2"]
// And if you want the closing parenthesis as Fabrício Matté mentioned
var elements = "Cu(NO3)2(CO2)3".match(/\(.*?\)/g);
elements = elements.map(function(match) { return match.substr(1); })
["NO3)", "CO2)"]
Your regex has anchors to match beginning and end of the string, so it won't suffice to match multiple occurrences. Updated code using String.match with the RegExp g flag (global modifier):
var userIn = 'Cu(NO3)2(CO2)3';
var inPar = userIn.match(/\([^)]*\)/g).map(function(s){ return s.substr(1); });
inPar; //["NO3)", "CO2)"]
In case you need old IE support: Array.prototype.map polyfill
Or without polyfills:
var userIn = 'Cu(NO3)2(CO2)3';
var inPar = [];
userIn.replace(/\(([^)]*\))/g, function(s, m) { inPar.push(m); });
inPar; //["NO3)", "CO2)"]
Above matches a ( and captures a sequence of zero or more non-) characters, followed by a ) and pushes it to the inPar array.
The first regex does essentially the same, but uses the entire match including the opening ( parenthesis (which is later removed by mapping the array) instead of a capturing group.
From the question I assume the closing ) parenthesis is expected to be in the resulting strings, otherwise here are the updated solutions without the closing parenthesis:
For the first solution (using s.slice(1, -1)):
var inPar = userIn.match(/\([^)]*\)/g).map(function(s){ return s.slice(1, -1);});
For the second solution (\) outside of capturing group):
userIn.replace(/\(([^)]*)\)/g, function(s, m) { inPar.push(m); });
You could try the below:
"Cu(NO3)2".match(/(\S\S\d)/gi) // returns NO3
"Cu(NO3)2(CO2)3".match(/(\S\S\d)/gi) // returns NO3 CO2
I was wondering how to use a regexp to match a phrase that comes after a certain match. Like:
var phrase = "yesthisismyphrase=thisiswhatIwantmatched";
var match = /phrase=.*/;
That will match from the phrase= to the end of the string, but is it possible to get everything after the phrase= without having to modify a string?
You use capture groups (denoted by parenthesis).
When you execute the regex via match or exec function, the return an array consisting of the substrings captured by capture groups. You can then access what got captured via that array. E.g.:
var phrase = "yesthisismyphrase=thisiswhatIwantmatched";
var myRegexp = /phrase=(.*)/;
var match = myRegexp.exec(phrase);
alert(match[1]);
or
var arr = phrase.match(/phrase=(.*)/);
if (arr != null) { // Did it match?
alert(arr[1]);
}
phrase.match(/phrase=(.*)/)[1]
returns
"thisiswhatIwantmatched"
The brackets specify a so-called capture group. Contents of capture groups get put into the resulting array, starting from 1 (0 is the whole match).
It is not so hard, Just assume your context is :
const context = "https://example.com/pa/GIx89GdmkABJEAAA+AAAA";
And we wanna have the pattern after pa/, so use this code:
const pattern = context.match(/pa\/(.*)/)[1];
The first item include pa/, but for the grouping second item is without pa/, you can use each what you want.
Let try this, I hope it work
var p = /\b([\w|\W]+)\1+(\=)([\w|\W]+)\1+\b/;
console.log(p.test('case1 or AA=AA ilkjoi'));
console.log(p.test('case2 or AA=AB'));
console.log(p.test('case3 or 12=14'));
If you want to get value after the regex excluding the test phrase, use this:
/(?:phrase=)(.*)/
the result will be
0: "phrase=thisiswhatIwantmatched" //full match
1: "thisiswhatIwantmatched" //matching group