JS: String.prototype.startsWith

New in JS2015.

str.startsWith(searchString)

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

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

str.startsWith(searchString, position)

Check if start from position.

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