JAVASCRIPT

regex match exact string

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*

regex.match

const paragraph = 'The quick brown fox jumps over the lazy dog. It barked.';
const regex = /[A-Z]/g;
const found = paragraph.match(regex);

console.log(found);
// expected output: Array ["T", "I"]

match regex

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
}

regex exact match

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

string.regex match

const str = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
const regexp = /[A-E]/gi;
const matches_array = str.match(regexp);

console.log(matches_array);
// ['A', 'B', 'C', 'D', 'E', 'a', 'b', 'c', 'd', 'e']