how to check if string contains letters javascript code example

Example 1: javascript string contains function

s = "Hello world";
console.log(s.includes("world"));

Example 2: javascript contains substring

var str = "We got a poop cleanup on isle 4.";
if(str.indexOf("poop") !== -1){
	alert("Not again");
}
//use indexOf (it returns position of substring or -1 if not found)

Example 3: js check if string contains character

"FooBar".includes("oo"); // true

"FooBar".includes("foo"); // false

"FooBar".includes("oo", 2); // false

Example 4: string contains js

var str = "foobar"
var regex = /foo/g;
if (str.search(regex) !== -1) {
  alert("string conains foo!")
}