Q:

How to match a substring surrounded by known prefix and suffix in javascript

Given a string, such as:

example string with an intended nested string to match.

How to isolate a substring knowing only a prefix and suffix for it, e.g. between intended and to match?

A:

Use regular expressions with non-capturing parentheses, like so:
string = 'example string with an intended nested string to match.';
regexp = /(?:intended)(.*)(?:to match)/;
firstMatch = regexp.exec(string)[1]; // " nested string "

The question mark has several uses in regular expressions, the parentheses question mark colon form (?:more regex) is the non-capturing parentheses.
See MDN for more details of exec(), string.match(), and regular expressions.

