I want to get the filename from an url. I'm doing this:
console.log(url)
const filename = url.match(/([^\/]+)(?=\.\w+$)/)[0]
return filename
But I get TypeError: Cannot read property '0' of null. Which is strange, because console.log(url) outputs the file: http://ac-0uhksb6K.clouddn.com/9710016c8dfcf6ae1e9d.jpg?imageView2/2/w/4096/h/2048/q/100/format/jpg
What could be the problem?
Your regex expects the filename with its extension to be the last part of a URL, while the URL in the question has also query parameters. In order to take these into account add the (?:$|\?) alternation to the lookahead:
[^\/]+(?=\.\w+(?:$|\?))
Note: the capture group is redundant so removed it as well.
Demo: https://regex101.com/r/nX2rP5/3
If there are no matches, then there is no array on which to select the first item with [0].
You'll want to check the array has at least one item first...
The error occurs because there is no match, see your regex demo. The issue is that the lookahead (?=\.\w+$) requires the .+1 or more word chars before the end of string $. You need to allow checking the ? query string start marker, too.
NOTE that you actually do not have to use lookarounds at all. Use a capturing group - ([^\/]+)\.\w+(?:\?|$) and access [1] item.
See the regex demo
Also, it is always a good idea to check if a match occurred at all before accessing capture groups.
var re = /([^\/]+)\.\w+(?:\?|$)/;
var str = 'file: http://ac-0uhksb6K.clouddn.com/9710016c8dfcf6ae1e9d.jpg?imageView2/2/w/4096/h/2048/q/100/format/jpg';
var match = str.match(re);
if (match) {
console.log(match[1]);
}
Related
I am passing a URL to a block of code in which I need to insert a new element into the regex. Pretty sure the regex is valid and the code seems right but no matter what I can't seem to execute the match for regex!
//** Incoming url's
//** url e.g. api/223344
//** api/11aa/page/2017
//** Need to match to the following
//** dir/api/12ab/page/1999
//** Hence the need to add dir at the front
var url = req.url;
//** pass in: /^\/api\/([a-zA-Z0-9-_~ %]+)(?:\/page\/([a-zA-Z0-9-_~ %]+))?$/
var re = myregex.toString();
//** Insert dir into regex: /^dir\/api\/([a-zA-Z0-9-_~ %]+)(?:\/page\/([a-zA-Z0-9-_~ %]+))?$/
var regVar = re.substr(0, 2) + 'dir' + re.substr(2);
var matchedData = url.match(regVar);
matchedData === null ? console.log('NO') : console.log('Yay');
I hope I am just missing the obvious but can anyone see why I can't match and always returns NO?
Thanks
Let's break down your regex
^\/api\/ this matches the beginning of a string, and it looks to match exactly the string "/api"
([a-zA-Z0-9-_~ %]+) this is a capturing group: this one specifically will capture anything inside those brackets, with the + indicating to capture 1 or more, so for example, this section will match abAB25-_ %
(?:\/page\/([a-zA-Z0-9-_~ %]+)) this groups multiple tokens together as well, but does not create a capturing group like above (the ?: makes it non-captuing). You are first matching a string exactly like "/page/" followed by a group exactly like mentioned in the paragraph above (that matches a-z, A-Z, 0-9, etc.
?$ is at the end, and the ? means capture 0 or more of the precending group, and the $ matches the end of the string
This regex will match this string, for example: /api/abAB25-_ %/page/abAB25-_ %
You may be able to take advantage of capturing groups, however, and use something like this instead to get similar results: ^\/api\/([a-zA-Z0-9-_~ %]+)\/page\/\1?$. Here, we are using \1 to reference that first capturing group and match exactly the same tokens it is matching. EDIT: actually, this probably won't work, since the text after /api/ and the text after /page/ will most likely be different, carrying on...
Afterwards, you are are adding "dir" to the beginning of your search, so you can now match someting like this: dir/api/abAB25-_ %/page/abAB25-_ %
You have also now converted the regex to a string, so like Crayon Violent pointed out in their comment, this will break your expected funtionality. You can fix this by using .source on your regex: var matchedData = url.match(regVar.source); https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/source
Now you can properly match a string like this: dir/api/11aa/page/2017 see this example: https://repl.it/Mj8h
As mentioned by Crayon Violent in the comments, it seems you're passing a String rather than a regular expression in the .match() function. maybe try the following:
url.match(new RegExp(regVar, "i"));
to convert the string to a regular expression. The "i" is for ignore case; don't know that's what you want. Learn more here:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp
I want to make sure that the URL I get from window.location does not already contain a specific fragment identifier already. If it does, I must remove it. So I must search the URL, and find the string that starts with mp- and continues until the end URL or the next # (Just in case the URL contains more than one fragment identifier).
Examples of inputs and outputs:
www.site.com/#mp-1 --> www.site.com/
www.site.com#mp-1 --> www.site.com
www.site.com/#mp-1#pic --> www.site.com/#pic
My code:
(that obviously does not work correctly)
var url = window.location;
if(url.toLowerCase().indexOf("#mp-") >= 0){
var imgString = url.substring(url.indexOf('#mp-') + 4,url.indexOf('#'));
console.log(imgString);
}
Any idea how to do it?
Something like this? This uses a regular expression to filter the unwanted string.
var inputs = [
"www.site.com/#mp-1",
"www.site.com#mp-1",
"www.site.com/#mp-1#pic"
];
inputs = inputs.map(function(input) {
return input.replace(/#mp-1?/, '');
});
console.log(inputs);
Output:
["www.site.com/", "www.site.com", "www.site.com/#pic"]
jsfiddle: https://jsfiddle.net/tghuye75/
The regex I used /#mp-1?/ removes any strings like #mp- or #mp-1. For a string of unknown length until the next hashtag, you can use /#mp-[^#]* which removes #mp-, #mp-1, and #mp-somelongstring.
Use regular expressions:
var url = window.location;
var imgString = url.replace(/(#mp-[^#\s]+)/, "");
It removes from URL hash anything from mp- to the char before #.
Regex101 demo
You can use .replace to replace a regular expression matching ("#mp-" followed by 0 or more non-# characters) with the empty string. If it's possible there are multiple segments you want to remove, just add a g flag to the regex.
url = url.replace(/#mp-[^#]*/, '');
The window.location has the hash property so... window.location.hash
The most primitive way is to declare
var char_start, char_end
and find two "#" or one and the 2nd will be end of input.
with that... you can do what you want, the change of window.location.hash will normally affect the browser adress.
Good luck!
I am trying to match everything after (but not including!) the last occurrence of a string in JavaScript.
The search, for example, is:
[quote="user1"]this is the first quote[/quote]\n[quote="user2"]this is the 2nd quote and some url https://www.google.com/[/quote]\nThis is all the text I\'m wirting about myself.\n\nLook at me ma. Javascript.
Edit: I'm looking to match everything after the last quote block. So I was trying to match everything after the last occurrence of "quote]" ? Idk if this is the best solution but its what i've been trying.
I'll be honest, i suck at this Regex stuff.. here is what i've been trying with the results..
regex = /(quote\].+)(.*)/ig; // Returns null
regex = /.+((quote\]).+)$/ig // Returns null
regex = /( .* (quote\]) .*)$/ig // Returns null
I have made a JSfiddle for anyone to have a play with here:
https://jsfiddle.net/au4bpk0e/
One option would be to match everything up until the last [/quote], and then get anything following it. (example)
/.*\[\/quote\](.*)$/i
This works since .* is inherently greedy, and it will match every up until the last \[\/quote\].
Based on the string you provided, this would be the first capturing group match:
\nThis is all the text I\'m wirting about myself.\n\nLook at me ma. Javascript.
But since your string contains new lines, and . doesn't match newlines, you could use [\s\S] in place of . in order to match anything.
Updated Example
/[\s\S]*\[\/quote\]([\s\S]*)$/i
You could also avoid regex and use the .lastIndexOf() method along with .slice():
Updated Example
var match = '[\/quote]';
var textAfterLastQuote = str.slice(str.lastIndexOf(match) + match.length);
document.getElementById('res').innerHTML = "Results: " + textAfterLastQuote;
Alternatively, you could also use .split() and then get the last value in the array:
Updated Example
var textAfterLastQuote = str.split('[\/quote]').pop();
document.getElementById('res').innerHTML = "Results: " + textAfterLastQuote;
I was able to build a regex to extract a part of a pattern:
var regex = /\w+\[(\w+)_attributes\]\[\d+\]\[own_property\]/g;
var match = regex.exec( "client_profile[foreclosure_defenses_attributes][0][own_property]" );
match[1] // "foreclosure_defenses"
However, I also have a situation where there will be a repetitive pattern like so:
"client_profile[lead_profile_attributes][foreclosure_defenses_attributes][0][own_property]"
In that case, I want to ignore [lead_profile_attributes] and just extract the portion of the last occurence as I did in the first example. In other words, I still want to match "foreclosure_defenses" in this case.
Since all patterns will be like [(\w+)_attributes], I tried to do a lookahead, but it is not working:
var regex = /\w+\[(\w+)_attributes\](?!\[(\w+)_attributes\])\[\d+\]\[own_property\]/g;
var match = regex.exec("client_profile[lead_profile_attributes][foreclosure_defenses_attributes][0][own_property]");
match // null
match returns null meaning that my regex isn't working as expected. I added the following:
\[(\w+)_attributes\](?!\[(\w+)_attributes\])
Because I want to match only the last occurrence of the following pattern:
[lead_profile_attributes][foreclosure_defenses_attributes]
I just want to grab the foreclosure_defenses, not the lead_profile.
What might I be doing wrong?
I think I got it working without positive lookahead:
regex = /(\[(\w+)_attributes\])+/
/(\[(\w+)_attributes\])+/
match = regex.exec(str);
["[a_attributes][b_attributes][c_attributes]", "[c_attributes]", "c"]
I was able to also achieve it through noncapturing groups. Output from chrome console:
var regex = /(?:\w+(\[\w+\]\[\d+\])+)(\[\w+\])/;
undefined
regex
/(?:\w+(\[\w+\]\[\d+\])+)(\[\w+\])/
str = "profile[foreclosure_defenses_attributes][0][properties_attributes][0][other_stuff]";
"profile[foreclosure_defenses_attributes][0][properties_attributes][0][other_stuff]"
match = regex.exec(str);
["profile[foreclosure_defenses_attributes][0][properties_attributes][0][other_stuff]", "[properties_attributes][0]", "[other_stuff]"]
Good evening, How can I find in javascript with regular expression string from url address for example i have url: http://www.odsavacky.cz/blog/wpcproduct/mikronebulizer/ and I need only string between last slashes (/ /) http://something.cz/something/string/ in this example word that i need is mikronebulizer. Thank you very much for you help.
You could use a regex match with a group.
Use this:
/([\w\-]+)\/$/.exec("http://www.odsavacky.cz/blog/wpcproduct/mikronebulizer/")[1];
Here's a jsfiddle showing it in action
This part: ([\w\-]+)
Means at least 1 or more of the set of alphanumeric, underscore and hyphen and use it as the first match group.
Followed by a /
And then finally the: $
Which means the line should end with this
The .exec() returns an array where the first value is the full match (IE: "mikronebulizer/") and then each match group after that.
So .exec()[1] returns your value: mikronebulizer
Simply:
url.match(/([^\/]*)\/$/);
Should do it.
If you want to match (optionally) without a trailing slash, use:
url.match(/([^\/]*)\/?$/);
See it in action here: http://regex101.com/r/cL3qG3
If you have the url provided, then you can do it this way:
var url = 'http://www.odsavacky.cz/blog/wpcproduct/mikronebulizer/';
var urlsplit = url.split('/');
var urlEnd = urlsplit[urlsplit.length- (urlsplit[urlsplit.length-1] == '' ? 2 : 1)];
This will match either everything after the last slash, if there's any content there, and otherwise, it will match the part between the second-last and the last slash.
Something else to consider - yes a pure RegEx approach might be easier (heck, and faster), but I wanted to include this simply to point out window.location.pathName.
function getLast(){
// Strip trailing slash if present
var path = window.location.pathname.replace(/\/$?/, '');
return path.split('/').pop();
}
Alternatively you could get using split:
var pieces = "http://www.odsavacky.cz/blog/wpcproduct/mikronebulizer/".split("/");
var lastSegment = pieces[pieces.length - 2];
// lastSegment == mikronebulizer
var url = 'http://www.odsavacky.cz/blog/wpcproduct/mikronebulizer/';
if (url.slice(-1)=="/") {
url = url.substr(0,url.length-1);
}
var lastSegment = url.split('/').pop();
document.write(lastSegment+"<br>");