Match from a class of characters

If you want to match against a set of characters, you can place the set inside []. For example, [abc] would mean any character a, b, or c:

var pattern = /[abc]/;
console.log(pattern.test('a')); //true
console.log(pattern.test('d')); //false

You can specify that you want to match anything but the pattern by adding a ^ (caret sign) at the beginning of the pattern:

var pattern = /[^abc]/;
console.log(pattern.test('a')); //false
console.log(pattern.test('d')); //true

One critical variation of this pattern is a range of values. If we want to match against a sequential range of characters or numbers, we can use the following pattern:

var pattern = /[0-5]/;
console.log(pattern.test(3)); //true
console.log(pattern.test(12345)); //true
console.log(pattern.test(9)); //false
console.log(pattern.test(6789)); //false
console.log(/[0123456789]/.test("This is year 2015")); //true

Special characters such as $ and period (.) characters...