javascript - if sentence contains string

If a sentence contains "Hello World" (no quotes) then I need to return true and do something. Possible sentences could be like this:

var sentence = "This is my Hello World and I like widgets."
var sentence = "Hello World - the beginning of all"
var sentence = "Welcome to Hello World"

if ( sentence.contains('Hello World') ){
alert('Yes');
} else {

alert('No');
}

I know the .contains does not work, so I'm looking for something does work. Regex is the enemy here.

Answer

The method you're looking for is indexOf (Documentation). Try the following

if (sentence.indexOf('Hello World') >= 0) { 
  alert('Yes');

} else { 
  alert('No');
}