Question: I am trying to some some urls throught javascript where some replacement of urls needs to be done. I have a textarea with some URLs example given below:

```
http://mywebsite.com/preview.aspx?mode=desktop&url=http://mywebsite.com/post.aspx?id=44&content=1
http://mywebsite.com/preview.aspx?mode=desktop&url=http://mywebsite.com/post.aspx?id=44&content=2
http://mywebsite.com/preview.aspx?mode=desktop&url=http://mywebsite.com/post.aspx?id=44&content=3
http://mywebsite.com/preview.aspx?mode=desktop&url=http://mywebsite.com/post.aspx?id=44&content=3

```

Now what i am trying to do is replacing `http://mywebsite.com/preview.aspx?mode=desktop&url=` with `spaces`.

I have tried using `str.replace()` but it is replacing only first occurence of that url.
I have also tried with Global variable `g` the query i have used is

```
str_replace(\http://mywebsite.com/preview.aspx?mode=desktop&url=/g,'');

```

But its not working So can anyone tell me how i can do that ?

I want the output of the textarea like:

```
http://mywebsite.com/post.aspx?id=44&content=1
http://mywebsite.com/post.aspx?id=44&content=2
http://mywebsite.com/post.aspx?id=44&content=3
http://mywebsite.com/post.aspx?id=44&content=4

```

Answer: 
I believe that your biggest issue is that your regex syntax is incorrect. Try this:

Imagine that `var s` is equal the the value of your textarea.

```
s.replace(/http\:\/\/mywebsite\.com\/preview.aspx\?mode\=desktop\&url\=/g, '');

```

The issue you were having was improper delimiters and unescaped reserved symbols.

Though Javascript has some of its own regex idiosyncrasies, the issues here were related to basic regex, you might find these resources useful:

<http://www.cheatography.com/davechild/cheat-sheets/regular-expressions/>

<http://regexpal.com>
try this.

```
var string = document.getElementById('textareaidhere');
 string.replace(/http:\/\/mywebsite\.com\/preview\.aspxmode=desktop&url=/g, '');

```

[JSFiddle here](http://jsfiddle.net/J8nEc/)