A quick example
var str = "Hello, this is a string!";
var result = str.startsWith("Hello");
var result2 = str.startsWith("Stein");
console.log('Result: ', result);
console.log('Result2: ', result2);
If you run this example in your browser, you will see that the first variable "result" is true because the string starts with "Hello". The second variable "result2" will be false, because the string does not start with "Stein".
It's worth mentioning that "startsWith" is a case sensitive search, so "hello" would return false too!
Search position
You can also use "startsWith" to check if a word is at a certain position in a string. That would look something like this:
var str = "Hello, this is a string!";
var result = str.startsWith("this", 7);
console.log('Result: ', result);
This would return "true". The parameter we passed in here after the word we want to check for has "0" as the default value. Therefor it will search at the beginning of a string as default.