Съвпадение на регулярен израз

//Declare Reg using slash
let reg = /abc/
//Declare using class, useful for buil a RegExp from a variable
reg = new RegExp('abc')

//Option you must know: i -> Not case sensitive, g -> match all the string
let str = 'Abc abc abc'
str.match(/abc/) //Array(1) ["abc"] match only the first and return
str.match(/abc/g) //Array(2) ["abc","abc"] match all
str.match(/abc/i) //Array(1) ["Abc"] not case sensitive
str.match(/abc/ig) //Array(3) ["Abc","abc","abc"]
//the equivalent with new RegExp is
str.match('abc', 'ig') //Array(3) ["Abc","abc","abc"]

const match = 'some/path/123'.match(/\/(\d+)/)
const id = match[1] // '123'

you want to achieve a case insensitive match for the word "rocket" 
surrounded by non-alphanumeric characters. A regex that would work would be:

\W*((?i)rocket(?-i))\W*

const regex = /([a-z]*)ball/g;
const str = "basketball football baseball";
let result;
while((result = regex.exec(str)) !== null) {
	console.log(result[1]); 
    // => basket
    // => foot
    // => base
}

use ^ and $ to match the start and end of your string
^matchmeexactly$

const str = 'For more information, see Chapter 3.4.5.1';
const re = /see (chapter \d+(\.\d)*)/i;
const found = str.match(re);

console.log(found);

// logs [ 'see Chapter 3.4.5.1',
//        'Chapter 3.4.5.1',
//        '.1',
//        index: 22,
//        input: 'For more information, see Chapter 3.4.5.1' ]

// 'see Chapter 3.4.5.1' is the whole match.
// 'Chapter 3.4.5.1' was captured by '(chapter \d+(\.\d)*)'.
// '.1' was the last value captured by '(\.\d)'.
// The 'index' property (22) is the zero-based index of the whole match.
// The 'input' property is the original string that was parsed.