Get text between two rounded brackets

console.log(
  "This is (my) simple text".match(/\(([^)]+)\)/)[1]
);

\( being opening brace, ( — start of subexpression, [^)]+ — anything but closing parenthesis one or more times (you may want to replace + with *), ) — end of subexpression, \) — closing brace. The match() returns an array ["(my)","my"] from which the second element is extracted.

For anyone looking to return multiple texts in multiple brackets

var testString = "(Charles) de (Gaulle), (Paris) [CDG]"
var reBrackets = /\((.*?)\)/g;
var listOfText = [];
var found;
while(found = reBrackets.exec(testString)) {
  listOfText.push(found[1]);
};

var txt = "This is (my) simple text";
re = /\((.*)\)/;
console.log(txt.match(re)[1]);​

jsFiddle example

You may also try a non-regex method (of course if there are multiple such brackets, it will eventually need looping, or regex)

init = txt.indexOf('(');
fin = txt.indexOf(')');
console.log(txt.substr(init+1,fin-init-1))