This assumes you are familiar with if statements in NodeJS. If not, check out my article NodeJS - Getting Started with if else statements.

Here is an example with an if statement using includes.

const my_string = "Hello World";

console.log(my_string.toLowerCase());

if (my_string.toLowerCase().includes('hello')) {
  console.log("my_string includes hello");
} else {
  console.log("my_string does NOT include hello");
}

And here is an example using the test method. This has the advantage of being able to pass in a regular expression so that multiple strings can be matched.

const my_string = "Hello World";

if (/hello|world/.test(my_string.toLowerCase())) {
  console.log("my_string includes hello or world");
} else {
  console.log("my_string does NOT include hello or world");
}