The match method retrieves the result of matching a string against a regular expression. An Array whose contents depend on the presence or absence of the global g flag, or null if no matches are found. If the regular expression does not include the g flag, str. In the following example, match is used to find ' Chapter ' followed by 1 or more numeric characters followed by a decimal point and numeric character 0 or more times.
The following example demonstrates the use of the global and ignore case flags with match. All letters A through E and a through e are returned, each its own element in the array.
Note: See also String. In browsers which support named capturing groups, the following code captures " fox " or " cat " into a group named " animal ":. When the regexp parameter is a string or a number, it is implicitly converted to a RegExp by using new RegExp regexp. If it is a positive number with a positive sign, RegExp will ignore the positive sign. Get the latest and greatest from MDN delivered straight to your inbox.
Sign in to enjoy the benefits of an MDN account. The source for this interactive example is stored in a GitHub repository. The compatibility table on this page is generated from structured data. Last modified: Mar 29,by MDN contributors.
Related Topics. Learn the best of web development Get the latest and greatest from MDN delivered straight to your inbox. The newsletter is offered in English only at the moment. Sign up now. Sign in with Github Sign in with Google. Chrome Full support 1. Edge Full support Firefox Full support 1. IE Full support 4. Opera Full support 4.When you search for data in a text, you can use this search pattern to describe what you are searching for. Regular expressions can be used to perform all types of text search and text replace operations.
Methods of RegExp and String
The search method searches a string for a specified value and returns the position of the match:. The replace method replaces a specified value with another value in a string:. Regular expression arguments instead of string arguments can be used in the methods above.
Powered by W3.Help to translate the content of this tutorial to your language! A part of a pattern can be enclosed in parentheses For instance, goooo or gooooooooo. The email format is: name domain. Any word can be the name, hyphens and dots are allowed. That regexp is not perfect, but mostly works and helps to fix accidental mistypes.
The only truly reliable check for an email can only be done by sending a letter. Parentheses are numbered from left to right. The search engine memorizes the content matched by each of them and allows to get it in the result. The method str.
Then groups, numbered from left to right by an opening paren. The first group is returned as result. Here it encloses the whole tag content. It looks for "a" optionally followed by "z" optionally followed by "c". If we run it on the string with a single letter athen the result is:.
The array length is permanent: 3. When we search for all matches flag gthe match method does not return contents for groups. The result is an array of matches, but without details about each of them. But in practice we usually need contents of capturing groups in the result. We can turn it into a real Array using Array.
There are more details about pseudoarrays and iterables in the article Iterables. The call to matchAll does not perform the search. Instead, it returns an iterable object, without the results initially. The search is performed each time we iterate over it, e.
Remembering groups by their numbers is hard. We have a much better option: give names to parentheses. Method str. In the example below we only get the name John as a separate member of the match:. Parentheses group together a part of the regular expression, so that the quantifier applies to it as a whole. Parentheses groups are numbered left-to-right, and can optionally be named with? If the parentheses have no name, then their contents is available in the match array by its number.Regular expressions are patterns used to match character combinations in strings.
Use the constructor function when you know the regular expression pattern will be changing, or you don't know the pattern and are getting it from another source, such as user input.
The last example includes parentheses, which are used as a memory device. The match made with this part of the pattern is remembered for later use, as described in Using groups. Simple patterns are constructed of characters for which you want to find a direct match. Such a match would succeed in the strings "Hi, do you know your abc's?
There is no match in the string "Grab crab" because while it contains the substring "ab c"it does not contain the exact substring "abc". When the search for a match requires something more than a direct match, such as finding one or more b's, or finding white space, you can include special characters in the pattern. The following pages provide lists of the different special characters that fit into each category, along with descriptions and examples.
If you want to look at all the special characters that can be used in regular expressions in a single table, see the following:. Character classes. Groups and ranges. Note: A larger cheatsheet is also available only aggregating parts of those individual articles. To match a literal backslash, you need to escape the backslash. If using the RegExp constructor with a string literal, remember that the backslash is an escape in string literals, so to use it in the regular expression, you need to escape it at the string literal level.
If escape strings are not already part of your pattern you can add them using String. The "g" after the regular expression is an option or flag that performs a global search, looking in the whole string and returning all matches.
It is explained in detail below in Advanced Searching With Flags. Parentheses around any part of the regular expression pattern causes that part of the matched substring to be remembered. Once remembered, the substring can be recalled for other use. See Groups and ranges for more details. Regular expressions are used with the RegExp methods test and exec and with the String methods matchreplacesearchand split.
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Use regex. But test seems to be faster as you can read here. I would recommend using the execute method which returns null if no match exists otherwise it returns a helpful object. Learn more. Check whether a string matches a regex in JS Ask Question. Asked 8 years, 9 months ago. Active 2 months ago. Viewed k times. Karol Selak 2, 3 3 gold badges 17 17 silver badges 40 40 bronze badges.
Richard Richard Do you want a complete match, or just whether the string contains a matching substring? A complete match - not a matching substring. Active Oldest Votes. Code Maniac So how would you do the opposite? PedroD stackoverflow. KeaganFouche 1 1 silver badge 6 6 bronze badges. Abhijeet Kasurde Abhijeet Kasurde 2, 1 1 gold badge 19 19 silver badges 30 30 bronze badges.
Note that the version with RegExp allows to inject variable values into the regex string. You can use match as well: if str. Important difference between match and test : match works only with strings, but test works also with integers.
The reason it works with a number is because the number is coerced into a string, because it's given as a parameter when it's expecting a string. I wouldn't rely on this behavior. It depends on your environment's implementation of test.
I'd reccomend explicitly converting your number to a string if you want to use it with a regex String for example. The most significant difference between test and match and matchAll is that match does things like to return a list of all matching sub-strings, while test only checks if there are any.The matchAll method returns an iterator of all results matching a string against a regular expressionincluding capturing groups.
The source for this interactive example is stored in a GitHub repository. An iterator which is not a restartable iterable.
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If you have ES9
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For those curious I'm trying to parse the database format of task warrior. If, for some mysterious reason, you need the additional information comes with execas an alternative to previous answers, you could do it with a recursive function instead of a loop as follows which also looks cooler. We are finally beginning to see a built-in matchAll function, see here for the description and compatibility table.
Seems like it was drafted in December so give it some time to reach all browsers, but I trust it will get there.
The built-in matchAll function is nice because it returns an iterable. It also returns capturing groups for every match! So you can do things like. It also seem like every match object uses the same format as match.
So each object is an array of the match and capturing groups, along with three additional properties indexinputand groups. So it looks like:. For more information about matchAll there is also a Google developers page.
Meaning if your system: Chrome, Node. Since ES9, there's now a simpler, better way of getting all the matches, together with information about the capture groups, and their index:.
It will return an array of all matches That would work just fine But remember it won't take groups in account. It will just return the full matches I would definatly recommend using the String. My example is with a list of strings, which is often necessary when scanning user inputs for keywords and phrases.
This isn't really going to help with your more complex issue but I'm posting this anyway because it is a simple solution for people that aren't doing a global search like you are. I've simplified the regex in the answer to be clearer this is not a solution to your exact problem. That looks more verbose than it is because of the comments, this is what it looks like without comments. Note that any groups that do not match will be listed in the array as undefined values.
This solution uses the ES6 spread operator to purify the array of regex specific values. You will need to run your code through Babel if you want IE11 support. My guess is that if there would be edge cases such as extra or missing spaces, this expression with less boundaries might also be an option:. If you'd like, you can also watch in this linkhow it would match against some sample inputs. If you want a more functional approach and to avoid looping you can just call a function until the result is null and on each capture you slice the string to the position of the captures group.
Learn more. RegEx to extract all matches from string using RegExp. Asked 8 years, 10 months ago. Active 2 months ago.