I've been playing around with Hubot for a bit, far too long actually but I'm getting stuck at matching a string in an array. replies is an array with some replies.
So this works:
module.exports = (robot) ->
robot.hear /seb/i, (msg) ->
msg.send msg.random replies
However, this does not:
regex = new RegExp triggers.join(), 'gi'
module.exports = (robot) ->
robot.hear regex, (msg) ->
msg.send msg.random replies
regex is a string made up of the contents of an array of strings. In this case printing out regex returns "/seb/i".
Anyone care to explain? I never was a big fan of JavaScript and Coffeescript :)
Array.prototype.join takes a string parameter as separator. It defaults to , when no parameter is given.
Let's assume we have the following array of keywords:
const triggers = ["kw1", "kw2", "kw3"]
Calling triggers.join() will return the string kw1,kw2,kw3. Passing that to RegExp constructor will create a RegExp object that matches the exact string kw1,kw2,kw3 (also ignores case because of the i flag).
In order to match multiple keywords with a regex, you must separate them with special-or (|) operator.
So instead of
regex = new RegExp triggers.join(), 'gi'
You should write
regex = new RegExp triggers.join('|'), 'i'
You might also want to drop the g (global search) flag as well, since it's enough to match the first occurrence of a keyword in your case.
Related
I'm doing a small javascript method, which receive a list of point, and I've to read those points to create a Polygon in a google map.
I receive those point on the form:
(lat, long), (lat, long),(lat, long)
So I've done the following regex:
\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)
I've tested it with RegexPal and the exact data I receive:
(25.774252, -80.190262),(18.466465, -66.118292),(32.321384, -64.75737),(25.774252, -80.190262)
and it works, so why when I've this code in my javascript, I receive null in the result?
var polygons="(25.774252, -80.190262),(18.466465, -66.118292),(32.321384, -64.75737),(25.774252, -80.190262)";
var reg = new RegExp("/\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)/g");
var result = polygons.match(reg);
I've no javascript error when executing(with debug mode of google chrome). This code is hosted in a javascript function which is in a included JS file. This method is called in the OnLoad method.
I've searched a lot, but I can't find why this isn't working. Thank you very much!
Use a regex literal [MDN]:
var reg = /\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)/g;
You are making two errors when you use RegExp [MDN]:
The "delimiters" / are should not be part of the expression
If you define an expression as string, you have to escape the backslash, because it is the escape character in strings
Furthermore, modifiers are passed as second argument to the function.
So if you wanted to use RegExp (which you don't have to in this case), the equivalent would be:
var reg = new RegExp("\\(\\s*([0-9.-]+)\\s*,\\s([0-9.-]+)\\s*\\)", "g");
(and I think now you see why regex literals are more convenient)
I always find it helpful to copy and past a RegExp expression in the console and see its output. Taking your original expression, we get:
/(s*([0-9.-]+)s*,s([0-9.-]+)s*)/g
which means that the expressions tries to match /, s and g literally and the parens () are still treated as special characters.
Update: .match() returns an array:
["(25.774252, -80.190262)", "(18.466465, -66.118292)", ... ]
which does not seem to be very useful.
You have to use .exec() [MDN] to extract the numbers:
["(25.774252, -80.190262)", "25.774252", "-80.190262"]
This has to be called repeatedly until the whole strings was processed.
Example:
var reg = /\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)/g;
var result, points = [];
while((result = reg.exec(polygons)) !== null) {
points.push([+result[1], +result[2]]);
}
This creates an array of arrays and the unary plus (+) will convert the strings into numbers:
[
[25.774252, -80.190262],
[18.466465, -66.118292],
...
]
Of course if you want the values as strings and not as numbers, you can just omit the +.
I'm doing a small javascript method, which receive a list of point, and I've to read those points to create a Polygon in a google map.
I receive those point on the form:
(lat, long), (lat, long),(lat, long)
So I've done the following regex:
\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)
I've tested it with RegexPal and the exact data I receive:
(25.774252, -80.190262),(18.466465, -66.118292),(32.321384, -64.75737),(25.774252, -80.190262)
and it works, so why when I've this code in my javascript, I receive null in the result?
var polygons="(25.774252, -80.190262),(18.466465, -66.118292),(32.321384, -64.75737),(25.774252, -80.190262)";
var reg = new RegExp("/\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)/g");
var result = polygons.match(reg);
I've no javascript error when executing(with debug mode of google chrome). This code is hosted in a javascript function which is in a included JS file. This method is called in the OnLoad method.
I've searched a lot, but I can't find why this isn't working. Thank you very much!
Use a regex literal [MDN]:
var reg = /\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)/g;
You are making two errors when you use RegExp [MDN]:
The "delimiters" / are should not be part of the expression
If you define an expression as string, you have to escape the backslash, because it is the escape character in strings
Furthermore, modifiers are passed as second argument to the function.
So if you wanted to use RegExp (which you don't have to in this case), the equivalent would be:
var reg = new RegExp("\\(\\s*([0-9.-]+)\\s*,\\s([0-9.-]+)\\s*\\)", "g");
(and I think now you see why regex literals are more convenient)
I always find it helpful to copy and past a RegExp expression in the console and see its output. Taking your original expression, we get:
/(s*([0-9.-]+)s*,s([0-9.-]+)s*)/g
which means that the expressions tries to match /, s and g literally and the parens () are still treated as special characters.
Update: .match() returns an array:
["(25.774252, -80.190262)", "(18.466465, -66.118292)", ... ]
which does not seem to be very useful.
You have to use .exec() [MDN] to extract the numbers:
["(25.774252, -80.190262)", "25.774252", "-80.190262"]
This has to be called repeatedly until the whole strings was processed.
Example:
var reg = /\(\s*([0-9.-]+)\s*,\s([0-9.-]+)\s*\)/g;
var result, points = [];
while((result = reg.exec(polygons)) !== null) {
points.push([+result[1], +result[2]]);
}
This creates an array of arrays and the unary plus (+) will convert the strings into numbers:
[
[25.774252, -80.190262],
[18.466465, -66.118292],
...
]
Of course if you want the values as strings and not as numbers, you can just omit the +.
I have a following string:
Text
I want to extract from this string, with the use of JavaScript 'pl' or 'pl_company_com'
There are a few variables:
jan_kowalski is a name and surname it can change, and sometimes even have 3 elements
the country code (in this example 'pl') will change to other en / de / fr (this is that part of the string i want to get)
the rest of the string remains the same for every case (beginning + everything after starting with _company_com ...
Ps. I tried to do it with split, but my knowledge of JS is very basic and I cant get what i want, plase help
An alternative to Randy Casburn's solution using regex
let out = new URL('https://my.domain.com/personal/jan_kowalski_pl_company_com/Documents/Forms/All.aspx').href.match('.*_(.*_company_com)')[1];
console.log(out);
Or if you want to just get that string with those country codes you specified
let out = new URL('https://my.domain.com/personal/jan_kowalski_pl_company_com/Documents/Forms/All.aspx').href.match('.*_((en|de|fr|pl)_company_com)')[1];
console.log(out);
let out = new URL('https://my.domain.com/personal/jan_kowalski_pl_company_com/Documents/Forms/All.aspx').href.match('.*_((en|de|fr|pl)_company_com)')[1];
console.log(out);
A proof of concept that this solution also works for other combinations
let urls = [
new URL('https://my.domain.com/personal/jan_kowalski_pl_company_com/Documents/Forms/All.aspx'),
new URL('https://my.domain.com/personal/firstname_middlename_lastname_pl_company_com/Documents/Forms/All.aspx')
]
urls.forEach(url => console.log(url.href.match('.*_(en|de|fr|pl).*')[1]))
I have been very successful before with this kind of problems with regular expressions:
var string = 'Text';
var regExp = /([\w]{2})_company_com/;
find = string.match(regExp);
console.log(find); // array with found matches
console.log(find[1]); // first group of regexp = country code
First you got your given string. Second you have a regular expression, which is marked with two slashes at the beginning and at the end. A regular expression is mostly used for string searches (you can even replace complicated text in all major editors with it, which can be VERY useful).
In this case here it matches exactly two word characters [\w]{2} followed directly by _company_com (\w indicates a word character, the [] group all wanted character types, here only word characters, and the {}indicate the number of characters to be found). Now to find the wanted part string.match(regExp) has to be called to get all captured findings. It returns an array with the whole captured string followed by all capture groups within the regExp (which are denoted by ()). So in this case you get the country code with find[1], which is the first and only capture group of the regular expression.
I am doing a challenge on freeCodeCamp. I am passed an array with 2 strings, the instructions are to test to see if the letters in the second string are in the first string.
Here's what I have:
return /[arr\[1\]]/gi.test(arr[0]);
This passes all the tests except where it tries to match with a capital letter.
mutation(["hello", "Hello"]) should return true.
It's the only test that fails, I have tested my regex on regexr.com with:
/[Hello]/gi and it matches with 'hello'.
Yes, there are other ways to do it, but why does it fail when I pass the string into the regex from the array?
EDIT: https://learn.freecodecamp.org/javascript-algorithms-and-data-structures/basic-algorithm-scripting/mutations
keep in mind that with this: return /[arr\[1\]]/gi.test(arr[0]) you are evaluating exactly this string "arr[1]". test() is a method of RegExp, then to add variables in a regex, or build the regex as string, you should use the RegExp constructor. Like the example below.
See this for browser compatibility of flags.
function mutation(str){
var r = new RegExp(str[0].toLowerCase(), "gi")
return r.test(str[1].toLowerCase());
}
console.log(mutation(["hello", "Hello"]))
The fact that your code passes the test for ["Mary", "Army"] shows that the problem is not one of case sensitivity. The only reason your code passes any of the tests is that /[arr\[1\]]/ looks for matches against the set of characters ar1[] which coincidentally happens to correctly match 8 of the 9 tests. Anyway the other - perhaps biggest - issue is that you are not testing all of the characters in arr[1] against arr[0]; if you run #Emeeus's answer it returns false positives for many of the tests. So, to test all of the characters in arr[1] against arr[0] you need something like this:
function mutation(arr) {
return arr[1].split('').reduce((t, c) => t && new RegExp(c, 'i').test(arr[0]), true);
}
let tests = [
['hello', 'hey'],
["hello", "Hello"],
["zyxwvutsrqponmlkjihgfedcba", "qrstu"],
["Mary", "Army"],
["Mary", "Aarmy"],
["Alien", "line"],
["floor", "for"],
["hello", "neo"],
["voodoo", "no"]
];
tests.map(arr => console.log(arr[0] + ", " + arr[1] + " => " + (mutation(arr) ? 'match' : 'no match')));
JavaScript has a special syntax for Regular Expressions. Those two lines are essentially the same:
return /[arr\[1\]]/gi.test(arr[0]);
return new RegExp('[arr\\[1\\]]', 'gi').test(arr[0]);
but what you probably want is this:
new RegExp('['+arr[1]+']', 'gi').test(arr[0]);
However, you should be careful since this approach does not work if it contains special characters such as '[' or ']'.
Whenever you have a javascript variable in a regular expression, you should construct a new RegExp object. Taken from your question, it should look like this
return new RegExp(arr[1], "gi").test(arr[0]);
As one hint on freeCodeCamp.org says, you can solve the problem easier if you transform the strings into arrays, using the spread operator. No need for regular expressions.
Instead of:
return /[arr\[1\]]/gi.test(arr[0]);
you can do:
return new RegEx(arr[1], gi);
Your code uses a character match ([ ]), not a string match, so it will match anything, that has those characters directly (That's why uppercase and lowercase differs, although you have specified 'i').
The new expression directly uses the string to match, not just the characters.
I want to check if a variable do not match this regexp:
DEMO
So this is the pattern that match the regexp in my code:
rxAfterPrint = new RegExp(/^ *\+ *("(?:[^"]*)"|(?:[a-zA-Z]\w*)) *(.*)$/);
and in this way I check for matching:
var t2 = t[2].match(rxAfterPrint);
and now I want to create e varible t3 that dont match this pattern
How can I do this? can you please help me?
(Admitting I have an unfair advantage because I knew why this problem did arise: How can I interpret strings in textarea with JavaScript/jQuery?)
So my guess is you want to implement String concatenation as part of a print statement as follows:
<string> ::= '"' <character>* '"' | <variable>
<print> ::= 'print' <string> ('+' <string>)*
<print> ::= 'print' (<string> '+')* <string>
The two <print> actually express the same, using the 2nd version you can first (after matching /^ *print */) try to apply the pattern rxConcat as many times a possible and if this doesn't match, then you apply the 2nd expression rxStringValEOL to match the remainder (if no success, it's an invalid statement):
rxConcat = new RegExp(/ *(?:"([^"]*)"|([a-zA-Z]\w*)) *\+ */);
rxStringValEOL = new RegExp(/ *(?:"([^"]*)"|([a-zA-Z]\w*)) *$/);
This also shows that it is pretty difficult to design a language that is easy for the programmers and for those who write the compilers.
It's really unclear what you mean by "I want to create a variable that don't match this pattern". Since t2 is your match, it seems like you want t3 to be objects that don't match.
Because you're anchoring to the start of the string (^), this is a really great place to use a negative lookahead with almost the identical regex. Literally, all I did was surround it with (?! and ) and .* at the end..
output1.value = input.value.match(/^(?! *\+ *("(?:[^"]*)"|(?:[a-zA-Z]\w*)) *(.*)).*$/gm).join("\r\n")
An alternative is to use replace() like so, but I would believe match() is the better option.
output2.value = input.value.replace(/(^ *\+ *("(?:[^"]*)"|(?:[a-zA-Z]\w*)) *(.*)$\s*)+/gm,"")
For both cases, I added the global and multiline to easily test several lines at once. If you're only testing one, remove both the g and the m, otherwise it could cause bugs by incorrectly telling you a string passed or failed when it didn't.
Demo: JSFiddle