JavaScript: String.prototype.startsWith

New in JS2015.

str.startsWith(searchString)

Return true if str starts with searchString. Else, return false.

str.startsWith(searchString, position)

Check if start from position.

const ss = "abcd";

console.log(ss.startsWith("ab"));
console.log(ss.startsWith("b") === false);

console.log(ss.startsWith("b", 1));