JAVASCRIPT

how to check if a string contains a certain letter in js

// use the variable.includes() 
const myString = "hello world!"
if(myString.includes("hello")){
  // do something 
}else{
  //also do something
}

check if specific letter exist in string javascript

// With ES6 MDN docs .includes()
"FooBar".includes("oo"); // true
"FooBar".includes("foo"); // false
"FooBar".includes("oo", 2); // false (2 is the start position for the search)

// E: Not suported by IE - instead you can use the Tilde opperator ~ (Bitwise NOT) with .indexOf()
~"FooBar".indexOf("oo"); // -2
~"FooBar".indexOf("foo"); // 0
~"FooBar".indexOf("oo", 2); // 0 (parameter 2 is the start position for the search)