I can't figure out how to pull out multiple matches from the following example:
This code:
/prefix-(\w+)/g.exec('prefix-firstname prefix-lastname');
returns:
["prefix-firstname", "firstname"]
How do I get it to return:
[
["prefix-firstname", "firstname"],
["prefix-lastname", "lastname"]
]
Or
["prefix-firstname", "firstname", "prefix-lastname", "lastname"]
This will do what you want:
var str="prefix-firstname prefix-lastname";
var out =[];
str.replace(/prefix-(\w+)/g,function(match, Group) {
var row = [match, Group]
out.push(row);
});
Probably a mis-use of .replace, but I don't think you can pass a function to .match...
_Pez
Using a loop:
re = /prefix-(\w+)/g;
str = 'prefix-firstname prefix-lastname';
match = re.exec(str);
while (match != null) {
match = re.exec(str);
}
You get each match one at a time.
Using match:
Here, the regex will have to be a bit different, because you cannot get sub-captures (or I don't know how to do it with multiple matches)...
re = /[^\s-]+(?=\s|$)/g;
str = 'prefix-firstname prefix-lastname';
match = str.match(re);
alert(match);
[^\s-]+ matches all characters except spaces and dashes/hyphens only if they are followed by a space or are at the end of the string, which is a confition imposed by (?=\s|$).
You can find the groups in two steps:
"prefix-firstname prefix-lastname".match(/prefix-\w+/g)
.map(function(s) { return s.match(/prefix-(\w+)/) })
Related
I have an expression.
var expression = "Q101='You will have an answer here like a string for instance.'"
I have a regular expression that searches the expression.
var regEx = new regExp(/=|<>|like/)
I want to split the expression using the regular expression.
var result = expression.split(regExp)
This will return the following:
["Q101", "'You will have an answer here ", " a string for instance'"]
This is not what I want.
I should have:
["Q101", "'You will have an answer here like a string for instance'"]
How do I use the regular expression above to split only on the first match?
Since you only want to grab the two parts either side of the first delimiter it might be easier to use String.match and discard the whole match:
var expression = "Q101='You will have an answer here like a string for instance.'";
var parts = expression.match(/^(.*?)(?:=|<>|like)(.*)$/);
parts.shift();
console.log(parts);
expression = "Q101like'This answer uses like twice'";
parts = expression.match(/^(.*?)(?:=|<>|like)(.*)$/);
parts.shift();
console.log(parts);
JavaScript's split method won't quite do what you want, because it will either split on all matches, or stop after N matches. You need an extra step to find the first match, then split once by the first match using a custom function:
function splitMatch(string, match) {
var splitString = match[0];
var result = [
expression.slice(0, match.index),
expression.slice(match.index + splitString.length)
];
return result;
}
var expression = "Q101='You will have an answer here like a string for instance.'"
var regEx = new RegExp(/=|<>|like/)
var match = regEx.exec(expression)
if (match) {
var result = splitMatch(expression, match);
console.log(result);
}
While JavaScript's split method does have an optional limit parameter, it simply discards the parts of the result that make it too long (unlike, e.g. Python's split). To do this in JS, you'll need to split it manually, considering the length of the match —
const exp = "Q101='You will have an answer here like a string for instance.'"
const splitRxp = /=|<>|like/
const splitPos = exp.search(splitRxp)
const splitStr = exp.match(splitRxp)[0]
const result = splitPos != -1 ? (
[
exp.substring(0, splitPos),
exp.substring(splitPos + splitStr.length),
]
) : (
null
);
console.log(result)
I am writing js code to get array of elements after splitting using regular expression.
var data = "ABCXYZ88";
var regexp = "([A-Z]{3})([A-Z]{3}d{2})";
console.log(data.split(regexp));
It returns
[ 'ABCXYZ88' ]
But I am expecting something like
['ABC','XYZ','88']
Any thoughts?
I fixed your regex, then matched it against your string and extracted the relevant capturing groups:
var regex = /([A-Z]{3})([A-Z]{3})(\d{2})/g;
var str = 'ABCXYZ88';
let m = regex.exec(str);
if (m !== null) {
console.log(m.slice(1)); // prints ["ABC", "XYZ", "88"]
}
In your case, I don't think you can split using a regex as you were trying, as there don't seem to be any delimiting characters to match against. For this to work, you'd have to have a string like 'ABC|XYZ|88'; then you could do 'ABC|XYZ|88'.split(/\|/g). (Of course, you wouldn't use a regex for such a simple case.)
Your regexp is not a RegExp object but a string.
Your capturing groups are not correct.
String.prototype.split() is not the function you need. What split() does:
var myString = 'Hello World. How are you doing?';
var splits = myString.split(' ', 3);
console.log(splits); // ["Hello", "World.", "How"]
What you need:
var data = 'ABCXYZ88';
var regexp = /^([A-Z]{3})([A-Z]{3})(\d{2})$/;
var match = data.match(regexp);
console.log(match.slice(1)); // ["ABC", "XYZ", "88"]
Try this. I hope this is what you are looking for.
var reg = data.match(/^([A-Z]{3})([A-Z]{3})(\d{2})$/).slice(1);
https://jsfiddle.net/m5pgpkje/1/
I've seen many examples of this but didn't helped. I have the following string:
var str = 'asfasdfasda'
and I want to extract the following
asfa asfasdfa asdfa asdfasda asda
i.e all sub-strings starting with 'a' and ending with 'a'
here is my regular expression
/a+[a-z]*a+/g
but this always returns me only one match:
[ 'asdfasdfsdfa' ]
Someone can point out mistake in my implementation.
Thanks.
Edit Corrected no of substrings needed. Please note that overlapping and duplicate substring are required as well.
For capturing overlapping matches you will need to lookahead regex and grab the captured group #1 and #2:
/(?=(a.*?a))(?=(a.*a))/gi
RegEx Demo
Explanation:
(?=...) is called a lookahead which is a zero-width assertion like anchors or word boundary. It just looks ahead but doesn't move the regex pointer ahead thus giving us the ability to grab overlapping matches in groups.
See more on look arounds
Code:
var re = /(?=(a.*?a))(?=(a.*a))/gi;
var str = 'asfasdfasda';
var m;
var result = {};
while ((m = re.exec(str)) !== null) {
if (m.index === re.lastIndex)
re.lastIndex++;
result[m[1]]=1;
result[m[2]]=1;
}
console.log(Object.keys(result));
//=> ["asfa", "asfasdfasda", "asdfa", "asdfasda", "asda"]
parser doesnt goto previous state on tape to match the start a again.
var str = 'asfaasdfaasda'; // you need to have extra 'a' to mark the start of next string
var substrs = str.match(/a[b-z]*a/g); // notice the regular expression is changed.
alert(substrs)
You can count it this way:
var str = "asfasdfasda";
var regex = /a+[a-z]*a+/g, result, indices = [];
while ((result = regex.exec(str))) {
console.log(result.index); // you can instead count the values here.
}
I have a paragraph that could have 1 or more instances of "#" followed by different usernames. How can I find each instance of this in Javascript?
Something like this but it doesn't work yet:
var regexp = '/#([a-z0-9_]+)/i';
var post = "Hi #tom, where is #john and #nick?" ;
var match, matches = [];
while ((match = regexp.exec(post)) != null) {
matches.push(match.index);
}
console.log(matches);
Console log would read: #tom #john #nick
You have two mistakes in your code causing it not to work as you expect.
(1.) You need to remove the quotes from your regular expression and use the g (global) modifier. You can replace your character class to the shorter version \w and remove the case-insensitive modifier here.
var regexp = /#\w+/g
(2.) You need to reference the match instead of referencing the match.index
matches.push(match[0]);
Final solution:
var post = "Hi #tom, where is #john and #nick?";
var regexp = /#\w+/g
var match, matches = [];
while ((match = regexp.exec(post)) != null) {
matches.push(match[0]);
}
console.log(matches); //=> [ '#tom', '#john', '#nick' ]
Alternatively you can use the String.match method.
var post = 'Hi #tom, where is #john and #nick?',
result = post.match(/#\w+/g);
console.log(result); //=> [ '#tom', '#john', '#nick' ]
var RegTxt = "$f1$='test' AND f2='test2'";
alert(RegTxt.match(/\'[^\']*'/g))
returns the match correctely i:e 'test','test2' but how can i remove the single quote in the match.
This would be quite simple if JavaScript supported negative lookbehinds:
/(?<=').*?(?=')/
But unfortunately, it doesn't.
In cases like these I like to abuse String.prototype.replace:
// btw, RegTxt should start with a lowercase 'r', as per convention
var match = [];
regTxt.replace(/'([^']*)'/g, function($0, $1){
match.push($1);
});
match; // => ['test', 'test2']
Here is a crude solution to your problem.
var match = RegTxt.match(/\'[^\']*'/g)
match = match.substring(1, match.length - 2);
Trivial approach:
RegTxt.replace(/'/g, "")
using your regex:
RegTxt.replace(/\'([^\']*)'/g, "$1")
var matches = str.match(regex);
var newMatches = [];
for( i in matches )
{
var word = matches[i];
newMatches.push( word.substring(1,word.length-1))
}
newMatches will now contain the array you need.