Develop Reference

How to use a regular expression in this case [duplicate]

This question already has answers here:
How do you use a variable in a regular expression?
(27 answers)
Closed 2 months ago.
I want to check if a string-variable (called string) matches the following string: L-62000-64-000_0
My code looks like this:
let string = "L-62000-64-000_05641";
let part = 64;
const filter = new RegExp("^L-\d{5}-${part}-.+");
if (string.match(filter)) {
console.log("yes");
}
It is important, that the string starts with "L-". After this there should be a number with five digits and again a hyphen. The following two digits depend on a variable. After the variable there is again a hyphen. The rest of the string is not important for me. That's why I use the ".+"
The problem is, that this doesn't work and i don't know why...

if you want to use the part variable in the string, you need to use `` instead of ""
const filter = new RegExp(`^L-\d{5}-${part}-.+`);

You also need to add double \\ in this case
let string = 'L-62000-64-000_05641';
let part = 64;
const filter = new RegExp(`^L-\\d{5}-${part}-.+$`);
if (string.match(filter)) {
console.log("yes");
} else {
console.log("no");
}

How to preserve character case using string.replace()? [duplicate]

This question already has answers here:
Replace text but keep case
(11 answers)
Closed 2 years ago.
I am attempting to write a function that will replace all of the vowels in a string with another arbitrary vowel which is selected by an end user. So far, I have been able to write a function that will replace all of the vowels regardless of case, but I would like to be able to preserve the case during replace().
Here is an example of what I am doing right now.
var selectedVowel = "a";
var vowels = /[aeiouAEIOU]/gi;
function rep(string){
let newString = string.replace(vowels, selectedVowel);
return newString;
}
rep("FooBar Exe. unIt");
// returns "FaaBar axe. anat"
// Intended output should return "FaaBar Axe. anAt"
I have tried using Regular Expressions to modify the search criteria for replace() and selectedVowel, but I can't figure out how to use the right regex characters to achieve that end.
I have also looked into methods that use split() to replace the first letter of a word, but this method seems to be limited to the string's indexes, which are not known at the time of the function call.
Any suggestions?

String.prototype.replace() takes a function in place of the substitution string, which is called for each match.
You could write a function that checks each match and replaces it with selectedVowel as-is or uppercased, depending on the case of the matched string.
A little trick to check if a character is upper/lowercase is to compare it to the upper/lowercased version of itself, as in match === match.toUpperCase().
var selectedVowel = "a";
var vowels = /[aeiouAEIOU]/gi;
function rep(string){
return string.replace(vowels, match => {
if (match === match.toUpperCase()) {
return selectedVowel.toUpperCase()
}
return selectedVowel
});
}
console.log(rep("FooBar Exe. unIt")) //=> "FaaBar Axa. anAt"

Modifying a string with letters, parentheses and numbers [duplicate]

This question already has answers here:
Regular Expression to get a string between parentheses in Javascript
(10 answers)
Closed 4 years ago.
How can I modify this string:
"SRID=4326;POINT (-21.93038619999993 64.1444948)"
so it will return
"-21.93038619999993 64.1444948"
(and then I can split that)?
The numbers in the string can be different.
I've tried using .replace & split, but I couldn't get it to work properly. How can I make this happen using Javascript?

You can try with match and regex:
"SRID=4326;POINT (-21.93038619999993 64.1444948)".match(/\(([^)]+)\)/)[1]
// "-21.93038619999993 64.1444948"

I am not good using REGEXP but this could be a solution with pure split.
Hope it helps :>
var str = "SRID=4326;POINT (-21.93038619999993 64.1444948)" ;
var newStr = str.split('(')[1].split(')')[0];
console.log(newStr)

var new_string = string.replace("SRID=4326;POINT (", "");

You can use a regular expression. The first number is put in first, the second number is put in second.
const INPUT = "SRID=4326;POINT (-21.93038619999993 64.1444948)";
const REGEX = /SRID=\d+;POINT \((.+) (.+)\)/
const [_, first, second] = INPUT.match(REGEX);
console.log(first);
console.log(second);

Use match in replace [duplicate]

This question already has answers here:
Javascript string replace method. Using matches in replacement string
(2 answers)
Closed 3 years ago.
I need to put every non-alphabetic character between spaces.
I want to do this using RegExp, and I understand it enouch to select them all (/(^a-zA-Z )/g).
Is there a way to use the original match inside the replace?
(something like)
str.replace(/(^a-zA-Z )/g,/ \m /);
If not I will just loop over all of them, but I really want to know it it is possible.

Yes. You can give the String.prototype.replace() function a RegExp as it's search. You can also give it a function to handle replacing.
The function will give you the match as the first parameter, and you return what you want to change it to.
const original = 'a1b2c';
const replaced = original.replace(/([^a-z])/gi, match => ` ${match} `);
console.log(replaced);
If you just need to do something simple, you can also just use the $n values ($1, $2, etc) to replace based on the selected group (the sets of parentheses).
const original = 'a1b2c';
const replaced = original.replace(/([^a-z])/gi, ' $1 ');
console.log(replaced);

Yes, it is possible. You can use regex with group:
var text = '2apples!?%$';
var nextText = text.replace(/([^a-zA-Z])/g, ' $1 ');
console.log(nextText);

You can check replace function on this link
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace

How can I get the last character in a string? [duplicate]

This question already has answers here:
How can I get last characters of a string
(25 answers)
Closed 10 years ago.
If I have the following variable in javascript
var myString = "Test3";
what is the fastest way to parse out the "3" from this string that works in all browsers (back to IE6)

Since in Javascript a string is a char array, you can access the last character by the length of the string.
var lastChar = myString[myString.length -1];

It does it:
myString.substr(-1);
This returns a substring of myString starting at one character from the end: the last character.
This also works:
myString.charAt(myString.length-1);
And this too:
myString.slice(-1);

var myString = "Test3";
alert(myString[myString.length-1])
here is a simple fiddle
http://jsfiddle.net/MZEqD/

Javascript strings have a length property that will tell you the length of the string.
Then all you have to do is use the substr() function to get the last character:
var myString = "Test3";
var lastChar = myString.substr(myString.length - 1);
edit: yes, or use the array notation as the other posts before me have done.
Lots of String functions explained here

myString.substring(str.length,str.length-1)
You should be able to do something like the above - which will get the last character

Use the charAt method. This function accepts one argument: The index of the character.
var lastCHar = myString.charAt(myString.length-1);

You should look at charAt function and take length of the string.
var b = 'I am a JavaScript hacker.';
console.log(b.charAt(b.length-1));