startsWith string method with empty searchString

Question

Why does startsWith method return true when the searchString is empty. I think same in other string methods like includes, endsWith. What can I do if I want to avoid it i.e. it should return false in case of empty searchString.

var haystack = 'Hello World!', needle ='';
console.log( haystack.startsWith( needle ) );

possible to duplicate https://stackoverflow.com/questions/145509/why-does-abcd-startswith-return-true — Narendra Jadhav, Mar 30 '18 at 04:01
Possible duplicate of [Why does "abcd".StartsWith("") return true?](https://stackoverflow.com/questions/145509/why-does-abcd-startswith-return-true) — Narendra Jadhav, Mar 30 '18 at 04:01

score 3 · Answer 1 · answered Mar 30 '18 at 03:18

3

Because it is designed to return so. Empty strings denote the existence of 0 characters. That's why, in a way, every string at least starts with blank.

If you still want to return false, you can do it like so:

var haystack = 'Hello World!',
  needle = '';
console.log(Boolean(needle) && haystack.startsWith(needle));

Check for the boolean equivalent of the checker string first, so that if it is blank, the return value becomes false.

answered Mar 30 '18 at 03:18

31piy

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You don't need `Boolean`. Empty string is falsy. – Tushar Mar 30 '18 at 03:24
1

@Tushar -- that's true, but `console.log` prints empty for that expression then. – 31piy Mar 30 '18 at 03:25

startsWith string method with empty searchString

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