Consider the following JS code:
if ( window.location.href == "https://teamtreehouse.com/signin" ) {
// do stuff...
}
I need that the comparison operator will not only cover the exact URL, but also any possible variation of it with query strings and data coming after the phrase "signin".
How will you do that in JS? I know it should include regex but as linear learning is important for me, I would prefer waiting to my course on JS regex in the coming weeks and just ask here, in this special occasion.
Try the following regex:
/^https:\/\/teamtreehouse\.com\/signin/i
The ^ means "starting with", and the extra \ characters are just to escape special characters inside the regex.
As per the comment by #epascarello, you should definitely use the "ignore-case" parameter, i (added above).
Edit:
Use the test function:
(/^https:\/\/teamtreehouse\.com\/signin/i).test(window.location.href)
You can use String#match to check if some string contains something.
Ex:
if (window.location.href.match("https://teamtreehouse.com/signin")){
// Do something
}
Also you can use this .host & .pathname from Window.location object.
Ex:
var link = window.location.host + window.location.pathname;
if (link === "www.teamtreehouse.com/signin"){
// Do something
}
if ( /^[https:\/\/teamtreehouse.com/signin][\?[\.]+]?/.test(window.location.href)) {
// do stuff...
}
Related
I'm trying to remove from my string all elements before an specific character which is repeated several times in this way:
let string = http://localhost:5000/contact-support
thus I´m just trying to remove everything before the third /
having as result:contact_support
for that i just set:
string.substring(string.indexOf('/') + 3);
Bust guess thats not the correct way
Any help about how to improve this in the simplest way please?
Thanks in advance!!!
It seems like you want to do some URL parsing here. JS brings the handful URL utility which can help you with this, and other similar tasks.
const myString = 'http://localhost:5000/contact-support';
const pathname = new URL(myString).pathname;
console.log(pathname); // outputs: /contact-support
// then you can also remove the first "/" character with `substring`
const whatIActuallyNeed = pathname.substring(1, pathname.length);
console.log(whatIActuallyNeed); // outputs: contact-support
Hope This will work
string.split("/")[3]
It will return the sub-string after the 3rd forward slash.
You could also use lastIndexOf('/'), like this:
string.substring(string.lastIndexOf('/') + 1);
Another possibility is regular expressions:
string.match(/[^\/]*\/\/[^\/]*\/(.*)/)[1];
Note that you must escape the slash, since it is the delimiter in regular expressions.
string.substring(string.lastIndexOf('/')+1) will also do the job if you are looking to use indexOf function explicitly.
Say I have the following url:
http://example.com/api
How can I create a regex that will match any url starting with that url segment above?
For example:
http://example.com/api/auth (should match)
http://example.com/api/orders (should match)
http://example.com/api/products (should match)
http://example.com/auth (should not match)
http://examples.com/api/auth (should not match)
https://example.com/api/auth (should not match)
Yes, obviously I could just call string.indexOf(url) == 0 to do a "starts with" check, but I specifically need a regular expression because I have to provide one to a third-party library.
The ^ modifier at the start of the expression means "string must start with":
/^http:\/\/example\.com\/api/
If you were using a different language which supports alternative delimiters, then it would probably be worth doing since the URL will contain /s in it. This doesn't work in Javascript (h/t T.J. Crowder) but does in languages like PHP (just mentioning it for completeness):
#^http://example\.com/api#
You could use this in JavaScript, though:
new RegExp("^http://example\\.com/api")
It's also worth noting that this will match http://example.com/apis-are-for-losers/something, because you're not testing for a / after api - just something to bear in mind. To solve that, you can use an alternation at the end requiring either that you be at the end of the string or that the next character be a /:
/^http:\/\/example\.com\/api(?:$|\/)/
new RegExp("^http://example\\.com/api(?:$|/)")
Why a regex if your search term is constant?
if (str.substr(0, 22) == 'http://example.com/api') console.log('OK');
^http:\/\/example\.com\/api.*
Regex link
Since it's javascript you can try this
var str = "You should match this string that starts with";
var res = str.match(/^You should match.*/);
alert(res);
You can use an 'anchor' to match the start (or end) of a string.
More info: http://www.regular-expressions.info/anchors.html
I'm trying to create a small script that detects whether the string input is either:
1) a URL (which will hold a filename): 'http://ajax.googleapis.com/html5shiv.js'
2) just a filename: 'html5shiv.js'
So far I've found this but I think it just checks the URL and file extension. Is there an easy way to make it so it uses an 'or' check? I'm not very experienced with RegExp.
var myRegExp = /[^\\]*\.(\w+)$/i;
Thank you in advance.
How bout this regex?
(\.js)$
it checks the end of the line if it has a .js on it.
$ denotes end of line.
tested here.
Basically, to use 'OR' in regex, simply use the 'pipe' delimiter.
(aaa|bbb)
will match
aaa
or
bbb
For regex to match a url, I'd suggest the following:
\w+://[\w\._~:/?#\[\]#!$&'()*+,;=%]*
This is based on the allowed character set for a url.
For the file, what's your definition of a filename?
If you want to search for strings, that match "(at least) one to many non-fullstop characters, followed by a fullstop, followed by (at least) one to many non-fullstop characters", I'd suggest the following regex:
[^\.]+\.[^\.]+
And altogether:
(\w+://[\w\._~:/?#\[\]#!$&'()*+,;=%]*|[^\.]+\.[^\.]+)
Here's an example of working (in javascript): jsfiddle
You can test it out regex online here: http://gskinner.com/RegExr/
If it is for the purpose of flow control you can do the following:
var test = "http://ajax.googleapis.com/html5shiv.js";
// to recognize http & https
var regex = /^https?:\/\/.*/i;
var result = regex.exec(test);
if (result == null){
// no URL found code
} else {
// URL found code
}
For the purpose of capturing the file name you could use:
var test = "http://ajax.googleapis.com/html5shiv.js";
var regex = /(\w+\.\w+)$/i;
var filename = regex.exec(test);
Yes, you can use the alternation operator |. Be careful, though, because its priority is very low. Lower than sequencing. You will need to write things like /(cat)|(dog)/.
It's very hard to understand what you exactly want with so few use/test cases, but
(http://[a-zA-Z0-9\./]+)|([a-zA-Z0-9\.]+)
should give you a starting point.
If it's a URL, strip it down to the last part and treat it the same way as "just a filename".
function isFile(fileOrUrl) {
// This will return everything after the last '/'; if there's
// no forward slash in the string, the unmodified string is used
var filename = fileOrUrl.split('/').pop();
return (/.+\..+/).test(filename);
}
Try this:
var ajx = 'http://ajax.googleapis.com/html5shiv.js';
function isURL(str){
return /((\/\w+)|(^\w+))\.\w{2,}$/.test(str);
}
console.log(isURL(ajx));
Have a look at this (requires no regex at all):
var filename = string.indexOf('/') == -1
? string
: string.split('/').slice(-1)[0];
Here is the program!
<script>
var url="Home/this/example/file.js";
var condition=0;
var result="";
for(var i=url.length; i>0 && condition<2 ;i--)
{
if(url[i]!="/" && url[i]!="."){result= (condition==1)? (url[i]+result):(result);}
else{condition++;}
}
document.write(result);
</script>
I have this regular expression
// Look for /en/ or /en-US/ or /en_US/ on the URL
var matches = req.url.match( /^\/([a-zA-Z]{2,3}([-_][a-zA-Z]{2})?)(\/|$)/ );
Now with the above regular express it will cause the problem with the URL such as:
http://mydomain.com/css/bootstrap.css
or
http://mydomain.com/js/jquery.js
because my regular expression is to strip off 2-3 characters from A-Z or a-z
My question is how would I add in to this regular expression to not strip off anything with
js or img or css or ext
Without impacting the original one.
I'm not so expert on regular expression :(
Negative lookahead?
var matches = req.url.match(/^\/(?!(js|css))([a-zA-Z]{2,3}([-_][a-zA-Z]{2})?)(\/|$)/ );
\ not followed by js or css
First of all you have not defined what exactly you are searching for.
Define an array with lowercased common language codes (Common language codes)
This way you'll know what to look for.
After that, convert your url to lowercase and replace all '_' with '-' and search for every member of the array in the resulting string using indexOf().
Since you said you're using the regex to replace text, I changed it to a replace function. Also, you forced the regex to match the start of the string; I don't see how it would match anything with that. Anyway, here's my approach:
var result = req.url.replace(/\/([a-z]{2,3}([-_][a-z]{2})?)(?=\/|$)/i,
function(s,t){
switch(t){case"js":case"img":case"css":case"ext":return s;}
return "";
}
);
Please help me solve this strange situation:
Here is code:
The link is so - www.blablabla.ru#3
The regex is so:
var id = window.location.href.replace(/\D/, '' );
alert(id);
The regular expression is correct - it must show only numbers ... but it's not showing numbers :-(
Can you please advice me and provide some informations on how to get only numbers in the string ?
Thanks
You're replacing only the first non-digit character with empty string. Try using:
var id = window.location.href.replace(/\D+/g, '' ); alert(id);
(Notice the "global" flag at the end of regex).
Consider using location.hash - this holds just the hashtag on the end of the url: "#42".
You can write:
var id = location.hash.substring(1);
Edit: See Kobi's answer. If you really are using the hash part of things, just use location.hash! (To self: Doh!)
But I'll leave the below in case you're doing something more complex than your example suggests.
Original answer:
As the others have said, you've left out the global flag in your replacement. But I'm worried about the expression, it's really fragile. Consider: www.37signals.com#42: Your resulting numeric string will be 3742, which probably isn't what you want. Other examples: www.blablabla.ru/user/4#3 (43), www2.blablabla.ru#3 (23), ...
How 'bout:
id = window.location.href.match(/\#(\d+)/)[1];
...which gets you the contiguous set of digits immediately following the hash mark (or undefined if there aren't any).
Use the flag /\D/g, globally replace all the instances
var id = window.location.href.replace(/\D/g, '' );
alert(id);
And /\D+/ gets better performance than /\D/g, according to Justin Johnson, which I think because of \D+ can match and replace it in one shot.