check if letter in string js code example

Example 1: check for substring javascript

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

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

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: js check if string contains character

if (your_string.indexOf('hello') > -1)
{
  alert("hello found inside your_string");
}

Example 5: check if something is a letter in js

string.charAt(1).toUpperCase() !== string.charAt(1).toLowerCase()