Question: What does the meaning of wrap here?

```
// wrap this with jQuery
var $foo = $(foo);

```

Answer: 
`$(foo)` constructs a new jQuery object every time it is called. You can save the value of `$(foo)` into a variable to cache it:

```
var $foo = $(foo);

```

In JavaScript, `$` is also a valid character for a variable name, so you can prefix variables which contain jQuery objects with `$`.

Without seeing the rest of the code, it's hard to say much more.
It means that you are taking the element (or selector, or whatever) named 'foo' and passing it to jQuery to create as a jQuery controlled object. This allows you to execute jQuery methods that will manipulate whatever foo is.

For example, if foo is a element, you cannot do this:

`foo.html('Hello World');` because foo is not a jQuery object.

You can, however, do this:

```
  var $foo = $(foo);
  $foo.html('Hello World');

```

and the innerHTML of the foo element will be set to 'Hello World'.