This question already has answers here:
Regex: Match desired chars at the beginning/end of string
(1 answer)
What do ^ and $ mean in a regular expression?
(2 answers)
Closed 3 years ago.
I want to select some words out of an array of words.
For example, the array is like below:
var list = ['Brothers', 'Browsers', 'Dermatologist','Specialist','Optometry']
I use below script to perform selection
var pattern = "Der";
var matched = list.filter(a => a.indexOf(pattern) >= 0);
The matched variable will contains:
['Dermatologist']
But when I change the pattern variable value to "ist" the result would be
['Dermatologist','Specialist']
I want my filtering to works only matching from the beginning of every word. So if I set pattern variable value to "Bro" it will returns
['Brothers','Browsers']
But when I set pattern variable value to "ers" it will returns empty array
[]
Can anybody help?
You can simply use startsWith
var list = ['Brothers', 'Browsers', 'Dermatologist','Specialist','Optometry']
var pattern = "Der";
var matched = list.filter(a => a.startsWith(pattern));
console.log(matched)
You can use a regex with ^ (which means beginning of line) before the pattern:
var list = ['Brothers', 'Browsers', 'Dermatologist','Specialist','Optometry'];
var pattern = /^Bro.*/;
var matched = list.filter(a => pattern.test(a));
console.log(matched);
Related
This question already has answers here:
javascript regex split produces too many items
(4 answers)
Closed 3 years ago.
Hi I have to split a string in two parts, the first one is always a char the second one is a number.
i.e.
a12
c4
I try to use this expression:
var myString = 'a12';
var mySplits = myString.split(/^([a-zA-Z]{1,2})([0-9]{1,2})$/);
console.log(mySplits);
the array expected is:
["a", "12"]
the result instead is:
["", "a", "12", ""]
I don't understand the reason why the result array has an empty value at start and at end.
Any help is really appreciated.
UPDATE
the solution proposed works but we can use a more elegant way.
ES18
With ES18 we could use the group capturing name
var myString = 'a12';
var matches =
/^(?<letter>[a-zA-Z]{1,2})(?<number>[0-9]{1,2})$/.exec(myString).concat();
console.log(matches.groups.letter);
console.log(matches.groups.number);
ES10
ES10 added the method .matchAll() that returns an Iterator, so if the need is not capture a single value but capture globally this method can be useful.
var myString = 'a12 b12 ';
for (const match of myString.matchAll(/(?<letter>[a-zA-Z]{1,2})(?<number>[0-9]{1,2})/g)) {
console.log(match.groups.letter);
console.log(match.groups.number);
}
var myString = 'a12';
var list = /^([a-zA-Z]{1,2})([0-9]{1,2})$/.exec(myString).concat();
list.shift(); // remove the first element
console.log(list); //This is the list that you want
This question already has answers here:
Get first letter of each word in a string, in JavaScript
(20 answers)
Closed 4 years ago.
I have a string like this:
DEBIT CARD. How can I extract the first letters of this string which is splitted by white space? To be more specific, I want the D and C parts of this string.
Use charAt(0) along with split():
split(/\s+/) will split the string into array structure based on whitespaces(single or multiple) so that you can loop over the elements of the array using map() and get the first character for each element. Then, finally you need to join('') the array and get the string representation.
var str = 'DEBIT CARD';
var res = str.split(/\s+/).map(x=>x.charAt(0)).join('');
console.log(res);
var stringg = 'DEBIT CARD';
var out = stringg.split(' ');
var required = out[1][0]; /* it will return only `C`, if you want the
first character of all letters just loop on `out` and get 0 index,
Here you can also use each loop or map and join functions to
achieve desired output.*/
console.log(required);
This question already has answers here:
How to grab substring before a specified character in JavaScript?
(12 answers)
Closed 6 years ago.
I am attempting to take the city out of a city, state string. For instance, "Portland, OR" would need to equal "Portland". How can I use Javascript or a regular expression to do this?
var myString = "Portland, OR";
I want to extract everything up to the comma but not including the comma.
var city = "Portland, OR".split(",")[0];
With regex:
var regex = /^[^,]+/;
var city = regex.exec("Portland, OR");
This is the regex version
var result = myString.match(/^[^,]+/)
UPDATE
This one always returns a value without error
var result = String(myString || "").match(/^[^,]*/)[0]
This question already has answers here:
My regex is matching too much. How do I make it stop? [duplicate]
(5 answers)
Closed 6 years ago.
I've got a couple strings and I need to pull characters out that appear between double quotes. The problem is, I want to grab them in groups.
var str = 'FF\"J"A4"L"';
var results = str.match(/\"(.*)\"/);
This returns everything between the first and last double quote. In this case it returns J"A4"L but what I need it to return is J and L.
The content between quotes is pretty much any unicode character like letters and numbers including as }, =, and #.
Any ideas on how to complete this with regex?
It sounds like the content between quotes is any character except for a quote, in which case you can get away with
/"([^"]*)"/
what you're looking for is this with the /g "global flag":
/("[^"]*")/g
In your example, it's like this:
var str = 'FF\"J"A4"L"';
var results = str.match(/("[^"]*")/g);
When doing this, results would be [""J"", ""L""], which contains the entire match (which is why the extra quotes are there).
If you wanted just the matched groups (which returns just the groups, not the whole match area), you would use exec:
var str = 'FF\"J"A4"L"';
var results = []
var r = /("[^"]*")/g
match = r.exec(str);
while (match != null) {
results.push(match[1])
match = r.exec(str);
}
Now, results is ["J", "L"]
This question already has answers here:
How do you access the matched groups in a JavaScript regular expression?
(23 answers)
Closed 8 years ago.
I got text like: do[A]and[B]
I want to extract all words that are wrapped by [ and ].
I am using the match method:
var text = "do[A]and[B]";
var regexp = /\[(\w+)\]/g;
var result = text.match(regexp);
So I am saying that I want to match all words wrapped by [ ], but only the wrapped part should be in group/memory. I keep getting the [ ] parentheses in result:
["[A]", "[B]"]
expected result is:
["A","B"]
I thought this is a piece of cake to do, but I must be missing something.
For this particular case you don't need capturing groups:
>>> "do[A]and[Bbbb]".match(/\w+(?=])/g);
["A", "Bbbb"]
will do.
In order to work with subpatterns, there is no easy shortcut.
Instead, you have to repeatedly execute the regex on the string and collect the subpattern you want. Something like this:
var text = "do[A]and[B]",
regexp = /\[(\w+)\]/g,
result = [], match;
while(match = regexp.exec(text)) {
result.push(match[1]);
}