String.prototype.startsWith

Checking a string starts with something is a fairly common task.

Currently you can check a string starts with something using .indexOf()

Checking the indexOf a particular string is 0, we know the string beings with that.

'https://blah.com'.indexOf('https') === 0; // true

'http://blah.com'.indexOf('https') === 0; // false

Now we can use the built in startsWith method making this a bit more reliable and more readable, our intent is much clearer.

'https://blah.com'.startsWith('https'); // true

Like indexOf, startsWith accepts an index. We could easily ignore the first 1/2 characters by passing in an index

'https://blah.com'.startsWith('blah', 8); // true