I'm trying to replace a part of a page with external content on the fly.

Here is the `source.html`:

```
<!DOCTYPE html>
<html>
  <head>
    <%= foobar %>
  </head>
  <body>
    This is body
  </body>
</html>

```

And a replacement string `inject.js`:

```
var REGEXP  = /^\'$/i; var foo = 1;

```

A ruby code that outputs a file by combining both.

```
pageContent = File.read('./source.html')
jsContent = File.read('./inject.js');
output = pageContent.gsub("<%= foobar %>", jsContent)
File.open('./dest.html', "w+") do |f|
  f.write(output)
end

```

However, I get the messed up `dest.html` which is happening because of `\'` in `inject.js`.

```
<!DOCTYPE html>
<html>
  <head>
    var REGEXP  = /^
  </head>
  <body>
    This is body
  </body>
</html>$/i; var foo = 1;
  </head>
  <body>
    This is body
  </body>
</html>

```

How do I get rid of this issue?