Removes all after the first block of numbers - javascript

I'm trying to write code that removes all after the first block of numbers and text.Do you have any idea how to do this.
string = '009EPMT18$MBS'
the expected result
string = '009EPMT'

You'll need regex to do that. It's a string analysis syntax common in many languages. There are many regular expressions which would do what you want, here's one:
var myRegex = /^[0-9]+[a-zA-Z]+/;
^ means that the search must begin at the start of the string.
[0-9] means that right after the beginning, there must be characters in the 0 to 9 range.
+ means there must be one or more of the previous condition, meaning there must be one or more digits.
[a-zA-Z] means there must be any character in the range a to z or A to Z. This won't include accented characters and letters from other alphabets though.
Calling .exec(string) on a regex returns an array of found strings in the passed string.

You were on the right track, the letters were just missing from your pattern:
var s = '009EPMT18$MBS';
var result;
var m = s.match(/^\d+[A-Z]+/); // first numbers and uppercase text
if (m) result = m[0]; // result = "009EPMT"
Regex explanation: beginning of string ^ followed by 1 or more digits \d+ followed by 1 or more letters from A to Z [A-Z]+. Note that lowercase characters will not match.

Related

Split a String by a Regex in JavaScript

I have the string:
"Vl.55.16b25.3d.42b50.59b30.90.24b35.3d.56.67b70.Tv.54b30.Vl.41b35.Tv.Bd.71b50.3d.99b20.03b50.Tv.73b50.Vl.05b25.12b40.Bd.Tv.82b25."
How to detached get results like:
["Vl.55.16b25", 3d.42.b50.59b30.90.24b35, 3d.56.67b70, ...]
The logic:
Condition 1: The End will be start b and 2 number. Example: b20, b25.
If pass condition 1 I need to check condition 2.
Condition 2: maybe like "3d" or 2 characters. If don't match condition 2 we need to pass the next character to the current block.
Many thanks.
If I understand your question correctly, the following code should work:
var string = "Vl.55.16b25.3d.42b50.59b30.90.24b35.3d.56.67b70.Tv.54b30.Vl.41b35.Tv.Bd.71b50.3d.99b20.03b50.Tv.73b50.Vl.05b25.12b40.Bd.Tv.82b25.";
console.log(string.split(/(?<=b\d\d)\.(?=3d)/g))
Explanation:
(?<=) is look-behind.
b matches the literal character "b".
\d matches any digit so \d\d will match two digits in a row.
\. matches a literal ".", it needs the \ before it because otherwise it would match any character.
(?=) is look-ahead.
The g flag stands for global so the string will be split up at every occurrence of the regular expression.
This means that the string will be split at every occurrence of "." that is preceded the letter "b" then two digits, and followed by "3d".
Assuming you want to separate by last having 'b' and two digits followed by 3d, two digits or the end of string (this is necessary) and by omitting leading dot, you could take the following regular expression.
const
string = "Vl.55.16b25.3d.42b50.59b30.90.24b35.3d.56.67b70.Tv.54b30.Vl.41b35.Tv.Bd.71b50.3d.99b20.03b50.Tv.73b50.Vl.05b25.12b40.Bd.Tv.82b25.",
result = string.match(/[^.].*?b\d\d(?=\.(3d|\D\D|$))/g);
console.log(result);

Regular expression for an alphanumeric word start with alphabet

I have a requirement to find and return the first occurrence of the pattern from a string.
Example: Please find my model number RT21M6211SR/SS and save it
Expected output: RT21M6211SR/SS
Condition for the pattern to match
Combination of digits and alphabets
Character length between 6 to 14
May or may not contain special characters like '-' or '/'
Starts with always alphabet
What I tried, but it didn't work for 4th condition
var str = 'Please find my model number RT21M6211SR/SS and save it';
var reg = /\b(\w|\d)[\d|\w-\/]{6,14}\b/;
var extractedMNO = '';
var mg = str.match(reg) || [""];
console.log('regular match mno', mg[0]);
\w matches word characters, which includes _ and digits as well. If you only want to match alphabetical characters, use [a-z] to match the first character.
Also, because you want to match lengths of 6-14, after matching the first character, you should repeat the character set with {5,13}, so that the repeated characters plus the first character comes out to a length of 6-14 characters.
var str = 'Please find my model number RT21M6211SR/SS and save it';
console.log(str.match(/\b[a-z][a-z0-9\/-]{5,13}/gi)[2]);
But since the matched string must contain digits (and doesn't just permit digits), then you need to make sure a digit exists in the matched substring as well, which you can accomplish by using lookahead for a digit right after matching the alphabetical at the start:
var str = 'Please find my model number RT21M6211SR/SS and save it';
console.log(str.match(/\b[a-z](?=[a-z\/-]{0,12}[0-9])[a-z0-9\/-]{5,13}/gi));
// ^^^^^^^^^^^^^^^^^^^^^^^
If you want to permit other special characters, just add them to the character set(s).

How does the following code mean two consecutive numbers?

This is from an exercise on FCC beta and i can not understand how the following code means two consecutive numbers seeing how \D* means NOT 0 or more numbers and \d means number, so how does this accumulate to two numbers in a regexp?
let checkPass = /(?=\w{5,})(?=\D*\d)/;
This does not match two numbers. It doesn't really match anything except an empty string, as there is nothing preceding the lookup.
If you want to match two digits, you can do something like this:
(\d)(\d)
Or if you really want to do a positive lookup with the (?=\D*\d) section, you will have to do something like this:
\d(?=\D*\d)
This will match against the last digit which is followed by a bunch of non-digits and a single digit. A few examples (matched numbers highlighted):
2 hhebuehi3
^
245673
^^^^^
2v jugn45
^ ^
To also capture the second digit, you will have to put brackets around both numbers. Ie:
(\d)(?=\D*(\d))
Here it is in action.
In order to do what your original example wants, ie:
number
5+ \w characters
a non-number character
a number
... you will need to precede your original example with a \d character. This means that your lookups will actually match something which isn't just an empty string:
\d(?=\w{5,})(?=\D*\d)
IMPORTANT EDIT
After playing around a bit more with a JavaScript online console, I have worked out the problem with your original Regex.
This matches a string with 5 or more characters, including at least 1 number. This can match two numbers, but it can also match 1 number, 3 numbers, 12 numbers, etc. In order to match exactly two numbers in a string of 5-or-more characters, you should specify the number of digits you want in the second half of your lookup:
let regex = /(?=\w{5,})(?=\D*\d{2})/;
let string1 = "abcd2";
let regex1 = /(?=\w{5,})(?=\D*\d)/;
console.log("string 1 & regex 1: " + regex1.test(string1));
let regex2 = /(?=\w{5,})(?=\D*\d{2})/;
console.log("string 1 & regex 2: " + regex2.test(string1));
let string2 = "abcd23";
console.log("string 2 & regex 2: " + regex2.test(string2));
My original answer was about Regex in a vacuum and I glossed over the fact that you were using Regex in conjunction with JavaScript, which works a little differently when comparing Regex to a string. I still don't know why your original answer was supposed to match two numbers, but I hope this is a bit more helpful.
?= Positive lookahead
w{5,} matches any word character (equal to [a-zA-Z0-9_])
{5,}. matches between 5 and unlimited
\D* matches any character that\'s not a digit (equal to [^0-9])
* matches between zero and unlimited
\d matches a digit (equal to [0-9])
This expression is global - so tries to match all
You can always check your expression using regex101

A regular expression that match a specified rules

I want a regular expression which accept 3 letters at least and 16 as max and which accept this following : all letters A to Z upper case and lower case and the .(dot) and numbers
I am using JavaScript
A simple regex to do this is the following:
^[A-Za-z0-9.]{3,16}$
The regex works as follows:
[A-Za-z0-9.] accepts any character you have specified;
{3,16} means repeating it 3 to 16 times; and
^ and $ means the start and end fo the string. So that it does not match other parts of the string.
Thus:
var str = "Wa89dadb...w";
var res = str.match(/^[A-Za-z0-9.]{3,16}$/g);

validating variable in javascript

Hi i have a field in php that will be validated in javascript using i.e for emails
var emailRegex = /^[\w-\.]+#([\w-]+\.)+[\w-]{2,4}$/;
What i'm after is a validation check which will look for the
first letter as a capital Q
then the next letters can be numbers only
then followed by a .
then two numbers only
and then an optional letter
i.e Q100.11 or Q100.11a
I must admit i look at the above email validation check and i have no clue how it works but it does ;)
many thanks for any help on this
Steve
The ^ marks the beginning of the string, $ matches the end of the string. In other words, the whole string should exactly match this regular expression.
[\w-\.]+: I think you wanted to match letters, digits, dots and - only. In that case, the - should be escaped (\-): [\w\-\.]+. The plus-sign makes is match one or more times.
#: a literal # match
([\w-]+\.)+ letters, digits and - are allowed one or more times, with a dot after it (between the parentheses). This may occur several times (at least once).
[\w-]{2,4}: this should match the TLD, like com, net or org. Because a TLD can only contain letters, it should be replaced by [a-z]{2,4}. This means: lowercase letters may occur two till four times. Note that the TLD can be longer than 4 characters.
An regular expression which should follow the next rules:
a capital Q (Q)
followed by one or more occurrences of digits (\d+)
a literal dot (.)
two digits (\d{2})
one optional letter ([a-z]?)
Result:
var regex = /Q\d+\.\d{2}[a-z]?/;
If you need to match strings case-insensitive, add the i (case-insensitive) modifier:
var regex = /Q\d+\.\d{2}[a-z]?/i;
Validating a string using a regexp can be done in several ways, one of them:
if (regex.test(str)) {
// success
} else {
// no match
}
var emailRegex = /^Q\d+\.\d{2}[a-zA-Z]?#([\w-]+\.)+[a-zA-Z]+$/;
var str = "Q100.11#test.com";
alert(emailRegex.test(str));
var regex = /^Q[0-9]+\.[0-9]{2}[a-z]?$/;
+ means one or more
the period must be escaped - \.
[0-9]{2} means 2 digits, same as \d{2}
[a-z]? means 0 or 1 letter
You can check your regex at http://regexpal.com/

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