Javascript regex match not working

Since your pattern is dynamically generated through string concatenation, you need to create a RegExp object:

var regex = new RegExp('^' + name + ');

You need to use RegExp object when you want to concatenate the query string. So in your case the / are part of the query.

 var regex = new RegExp('^' + name);
 var s = '';
 s = this.innerHTML.toString().toLowerCase().match(regex);
 if (s != null) {
   //do stuff
 }

I created a jsFiddle to allow you to test various regex aspects.

The problem is that the formatting of var regex is incorrect. Remove the /es:

// Test code
var name = "foobar";
//var test = "foobar at the start of a sentence";
var test = "a sentence where foobar isn't at the start";

//var regex = '/^' + name + '/'; // Wrong format
var regex = '^' + name; // correct format
var s = '';
//s = this.innerHTML.toString().toLowerCase().match(regex);
s = test.toString().toLowerCase().match(regex);
if (s != null) {
    //do stuff
    alert("works");
}

There are two ways to create a regular expression:

1) Using the literal form

var re = /\w+/;

2) Using object creation form

var re = new RegExp("\\w+");

Typically you will want the literal form. In your case were you are creating it from a string you must use the object creation form.

var re = new RegExp("^" + name);

Just removing the slashes works.

pattern = function(name){"^"+name;}

(name + "whatever").match(pattern(name)); // not null
("whatEver..NotName").match(pattern(name)); // null