let string = "Hello world"; // you can use .toLowerCase() to check only in lower
let match = "world"; // word to match
let regex = new RegExp('('+match+')');
console.log('true for no match, false for match');
console.log(string.match(regex) == null); //.match() returns array of words found
// true for no match, false for match
// false
let stringToSearch = 'looking for value';
let valueToFind = /off/gi
let isValueInString = Boolean(stringToSearch.match(valueToFind));