Short-circuit in starts_with

[ozanmuyes]

std/bytes/starts_with.ts

Line 27 in 10ee73d

if (prefix.length > source.length) {

this can be written as

         if (prefix.length != source.length) {

since prefix can't be longer than the source.

[babiabeo]

It will return false if prefix is shorter than source, which is not the expected behavior.

[ozanmuyes]

Why it is not the expected behaviour? So "foobar" starts with "foobarbaz"?

[0f-0b]

This is what happens if you run the example from the documentation after applying this change.

$ deno run example.ts
error: Uncaught (in promise) AssertionError: Values are not equal.


    [Diff] Actual / Expected


-   false
+   true

  throw new AssertionError(message);
        ^
    at assertEquals (file://…/deno_std/assert/equals.ts:51:9)
    at file://…/example.ts:7:1

If you remove the check altogether it would work, but much slower than the original in case prefix is sometimes longer than source, because V8 deoptimizes the function when source[i] indexes out of bounds.