We Keep Coding

Using RegExp to substring a string at the position of a special character

Suppose I have a sting like this: ABC5DEF/G or it might be ABC5DEF-15 or even just ABC5DEF, it could be shorter AB7F, or AB7FG/H.
I need to create a javascript variable that contains the substring only up to the '/' or the '-'. I would really like to use an array of values to break at. I thought maybe to try something like this.
...
var srcMark = array( '/', '-' );
var whereAt = new RegExp(srcMark.join('|')).test.str;
alert("whereAt= "+whereAt);
...
But this returns an error: ReferenceError: Can't find variable: array
I suspect I'm defining my array incorrectly but trying a number of other things I've been no more successful.
What am I doing wrong?

Arrays aren't defined like that in JavaScript, the easiest way to define it would be with:
var srcMark = ['/','-'];
Additionally, test is a function so it must be called as such:
whereAt = new RegExp(srcMark.join('|')).test(str);
Note that test won't actually tell you where, as your variable suggests, it will return true or false. If you want to find where the character is, use String.prototype.search:
str.search(new RegExp(srcMark.join('|'));
Hope that helps.

You need to use the split method:
var srcMark = Array.join(['-','/'],'|'); // "-|/" or
var regEx = new RegExp(srcMark,'g'); // /-|\//g
var substring = "222-22".split(regEx)[0] // "222"
"ABC5DEF/G".split(regEx)[0] // "ABC5DEF"

From whatever i could understand from your question, using this RegExp /[/-]/ in split() function will work.
EDIT:
For splitting the string at all special characters you can use new RegExp(/[^a-zA-Z0-9]/) in split() function.
var arr = "ABC5DEF/G";
var ans = arr.split(/[/-]/);
console.log(ans[0]);
arr = "ABC5DEF-15";
ans = arr.split(/[/-]/);
console.log(ans[0]);
// For all special characters
arr = "AB7FG/H";
ans = arr.split(new RegExp(/[^a-zA-Z0-9]/));
console.log(ans[0]);

You can use regex with String.split.
It will look something like that:
var result = ['ABC5DEF/G',
'ABC5DEF-15',
'ABC5DEF',
'AB7F',
'AB7FG/H'
].map((item) => item.split(/\W+/));
console.log(result);
That will create an Array with all the parts of the string, so each item[0] will contain the text till the / or - or nothing.

If you want the position of the special character (non-alpha-numeric) you can use a Regular Expression that matches any character that is not a word character from the basic Latin alphabet. Equivalent to [^A-Za-z0-9_], that is: \W
var pattern = /\W/;
var text = 'ABC5DEF/G';
var match = pattern.exec(text);
var position = match.index;
console.log('character: ', match[0]);
console.log('position: ', position);

jQuery Regex from String

I have the following Regex that comes from a data Attribute on an HTML Element:
/^$|^[0-9]{2}.[0-9]{4}$/g
When I (manually) do:
/^$|^[0-9]{2}.[0-9]{4}$/g.test('01.2012');
It works and returns true.
When I put the Regex in a Variable like so:
var inputRegex = $(this).attr('data-validation');
And do:
inputRegex.test(input);
I get:
inputRegex.test is not a function.
I know that this is because inputRegex is a String and String does not have a test function, but when I create a RegExp object (new RegExp($(this).attr('data-validation')) it breaks my Regular Expression by escaping:
/\/^$|^[0-9]{2}.[0-9]{4}$\/g/
How can I use the data-attribute value as a Regular Expression? Please note that I cannot do: var regex = new RegExp(string, 'g'); because the Regular Expression(s) come predefined from the attribute.

var pattern = '\d+';
var regExp = new RegExp(pattern, 'g');
'1234dasf13241234'.match(regExp)
is it what you need?
var pattern = $(this).attr('data-validation');;
var regExp = new RegExp(pattern, 'g');
regExp.test(input);
in your case

your problem is that you need to retrieve the regex pattern from a attribute of an element, but it is returning string, and you want the string value to be like inline on your javascript code, like declaring plainly a regex. If this is really what you want to achieve, the closest solution is to use eval function, see updated code below:
var stringreg = "var inputRegex =" + $("#test").attr('data-validation') + ";"
eval(stringreg);
inputRegex.test(input);

This could help
var validation = "/^$|^[0-9]{2}.[0-9]{4}$/g"; //$(this).attr('data-validation')
var startIndex = validation.indexOf('/')+1
var lastIndex = validation.lastIndexOf('/');
var pattern = validation.substring(startIndex,lastIndex);
var options = validation.substring(lastIndex+1);
var regExp = new RegExp(pattern, options);
regExp.test('01.2012');
// true

Optimize regular expression for path replacement

I have following string var foo = require('foo/bar'); which I want to change to var foo = require('../../foo/bar');.
So far I wrote following code which would do this:
var search = 'foo/bar';
var replace = '../../foo/bar';
var regex = new RegExp('require[(](\"|\')' + search + '(\"|\')[)]', 'g');
var source = 'var foo = require(\'foo/bar\')';
source.replace(regex, 'require(\'' + replace + '\')');
However as you see this is very inefficient. What could I do to make this regex a bit shorter. For example:
only have to replace the path and not to rewrite require with require(\'' + replace + '\')'
make (\"|\') and [(] shorter
anything else?
Best,
Bo
Edit:
I am doing this replacement on complete javascript source files.
Edit2:
What is necessary to change var foobar = require('foo/bar'); to var foobar = require('../../foo/baz/bar') when foo/ and ../../foo/baz/ should be variable?

You can use this code:
var search = 'foo/bar';
var source = "var foo = require('foo/bar')";
var regex = new RegExp('(require)\\((["\'])(' + search + ')\\2\\)', 'g');
var repl = source.replace(regex, "$1('../../$3')");
//=> var foo = require('../../foo/bar')

Here is an alternative :
var str = "var foo = require('foo/bar');";
str = str.split(/(')/);
str.splice(2, 0, '../../');
str = str.join('');
Even simpler :
"var foo = require('foo/bar');".replace(/'([^']+)'/, "'../../$1'")

I wonder if you could do the replacement before wrapping your path inside the var xxx = require() statement.
Optimizing code that starts by undoing what has been done just before seems a bit inefficient.
Besides, it seems you already know the target path (foo/bar in your example), but it is not even necessary to use that.
The regexp here boils down to splitting the string after the opening quote and inserting the ../../ prefix.
You could do that with
source = source.split(/["']/,2).join('"../../')+'");';
The regexp is a constant, so you could put it into a variable to have it compiled once and for all.
That would probably be more efficient than generating and recompiling the regexp from your example each time.
But anyway, I wonder how many such strings you would have to replace to start noticing a performance hit.

replace number after underscore

I nee to replace all numbers after underline inside a string.
I think that I can use Regex, but I don't know how to use Regex Syntax
See an example of my string:
milton_0
milton_1

If that is the standard format, You can use split()
var str = 'milton_1';
alert(str.split('_')[1]);

You don't need regex for this. The following code in enough
var str = "milton_0";
str = str.substring(0,str.indexOf("_"));

I'm not sure how specific or broad you want to be, but you can try this:
var starter = "milton_1";
var specialVal = "asdf";
var re = /^(milton_)(\d+)$/;
var replaced = starter.replace(re, function (match, p1) {
return p1 + specialVal;
});
console.log(replaced);
http://jsfiddle.net/ne4cD/
This will match a string starting with "milton_" and ending with digits. It replaces any digits after the "_" with the specialVal value.
An example of simply incrementing that number is:
var starter = "milton_1";
var re = /^(milton_)(\d+)$/;
var replaced = starter.replace(re, function (match, p1, p2) {
return p1 + (+p2 + 1);
});
console.log(replaced);
http://jsfiddle.net/ne4cD/2/
UPDATE:
If the "milton" part isn't static, then you're really only targeting the "_" with digits after it. So something like this:
var starter = "asdfkjlasdfjksadf_1";
var specialVal = "asdf";
var re = /(_)(\d+)/g;
var replaced = starter.replace(re, function (match, p1) {
return p1 + specialVal;
});
console.log(replaced);
http://jsfiddle.net/ne4cD/3/
And maybe a little better to see: http://jsfiddle.net/ne4cD/4/

First of all you need them as list for handling easily.
var listOfStrings = yourStringObject('whateverYourCharacterUnderEachWord').ToList<string>();
After that you need to get rid of number for each string in the list and add what you want.
foreach(string word in listOfStrings){
word = word.Substring(0,word.IndexOf('_')+1);
word = word + "characterThatYouWantToAddHere"
}

Creating a dynamic RegExp pattern to include a variable value

I have a RegExp that I would like to make dynamic and create in a string. I want to change this:
var result:Object = value.match(/John\/(.*?) /);
to this:
var firstName:String = "John";
var result:Object = value.match(firstName + "\/(.*?) "); // this doesn't work
I'm using ActionScript but I think what would work in JavaScript would work as well here.

In Javascript you can create a new instance of the RegExp class:
var firstName:String = "John";
var result:Object = value.match(new RegExp(firstName + "\/(.*?) "));
When you use value.match(firstName + "\/(.*?) "); the first parameter to the match function is a string, but it should be a regular expression object.