How can I correctly check if a string does NOT contain a specific word?

Question

I am currently trying to figure out how to solve the above named problem. Specifically I want to check if the string does not contain the word \"stream\" both in ca

Answer 1

indexOf() is the correct approach and the case issue can be easily resolved by forcing the test string to lower or upper case before the test using .toLowerCase() or .toUpperCase():

const lookupValue = "stream";
const testString1 = "I might contain the word StReAm and it might be capitalized any way.";
const testString2 = "I might contain the word steam and it might be capitalized any way.";

function testString(testData, lookup){
  return testData.toLowerCase().indexOf(lookup) === -1;
}

function prettyPrint(yesNo){
   return "The string does" + (yesNo ? " NOT" : "") + " contain \"stream\" in some form."
}

console.log(prettyPrint(testString(testString1, lookupValue)));
console.log(prettyPrint(testString(testString2, lookupValue)));