get string between two strings with javascript [duplicate]

Question

How do I get a string between two strings using match with variables? The following code works well if I use match with strings Regular Expression to get a string between two strings in Javascript I also tried to apply the info at JavaScript - Use variable in string match :

var test = "My cow always gives milk";  var testRE = test.match("cow(.*)milk"); alert(testRE[1]); 

But what if I have:

var firstvariable = "cow"; var secondvariable = "milk";  var test = "My cow always gives milk"; 

I've tried various things including:

var testRE = test.match("firstvariable(.*)secondvariable"); alert(testRE[1]); 

and:

var testRE = testRE.match + '("' + firstvariable + "(.*)" + secondvariable +'")'; alert(testRE[1]); 

Neither worked.

Answer 1

Try this:

test.match(new RegExp(firstvariable + "(.*)" + secondvariable));