replace() regex

[codefossa]

I need help with regex, using a wildcard.

 

In PHP, it would be like this.

 

$str = 'sentence test&new';

$new = preg_replace('/(.*)&/', ''); // $new would now be equal to "new"

 

How would I do this same thing with str.replace() in javascript?

[Adam]

A 'wildcard' is a character that can take any value. What does the ampersand indicate here? Looks like you're trying to parse out the text after it?

[salathe]

"sentence test&new".replace(/(.*)&/, "")

[.josh]

"sentence test&new".replace(/(.*)&/g, "")

 

technically you need a g modifier on there.  By default, preg_replace() replaces all.  By default, .replace() does not.

 

...though based on context of the subject...it probably doesn't matter...

[salathe]

technically you need a g modifier on there.  By default, preg_replace() replaces all.  By default, .replace() does not.

 

Technically, it doesn't matter and is not needed; at least, not for this particular use. 

 

The only thing that I would change would be the dot, if the string can span multiple lines. The PHP code mentioned would also need to be modified in that case.

[codefossa]

Ohhhh, you don't put the regex inside of a string.  Thanks very much!

[salathe]

Ohhhh, you don't put the regex inside of a string.

 

Nope, JavaScript has a particular kind of object for regular expressions (see RegExp) and a "literal" syntax for creating new RegExp objects (e.g. /abc/g), as you've already seen.

 

Thanks very much!

 

You're welcome. 

[.josh]

To expand...(translation: salathe beat me but dammit i made a long post so I'm posting anyway!)

 

Ultimately, in javascript a regex pattern is actually an object.  So you can use the pattern directly in the .replace() like that because it will ultimately evaluate to a regex object.  However, you can setup a regex pattern, putting it in a "string" by creating a RegExp object...though in the end you are still creating an object.  So for example, you could alternatively do:

 

var str = 'sentence test&new';

// 2 arguments: "pattern", "modifiers"
var pattern = new RegExp("(.*)&","g");

str = str.replace(pattern,'');

 

In this example, you are putting putting the pattern in quotes - as a string.  But again, ultimately this creates an object.  The main benefit of doing it this way over using the pattern directly as an object (no quotes, directly in .replace()) is if you want to make part of the pattern a variable. 

 

Example:

var subject = 'bargain';
var foo = 'bar';

// works : use a variable and the pattern is the value of the variable
var pattern = new RegExp(foo,"g");
str1 = subject.replace(pattern,'');
alert(str1); 
// output : 'gain'

// does not work : it looks for the literal string 'foo' 
str2 = subject.replace(/foo/g,'');
alert(str2);
// output : 'bargain'