js if string does not contain code example

Example 1: check for substring javascript

const string = "javascript";
const substring = "script";

console.log(string.includes(substring));  //true

Example 2: javascript string contains

var string = "foo",
    substring = "oo";

console.log(string.includes(substring));

Example 3: js string does not contain

"this is the string".indexOf("cake"); // -1 (does not contain)
"this string has cake".indexOf("cake"); // 16 (contains)