Drops elements from the beginning of an async iterable as long as a specified condition is met, and yields the remaining elements.

import { dropWhile } from "./drop.ts";

async function* gen() { yield "foo"; yield "bar"; yield "baz"; yield "qux" }
const iterable = dropWhile(gen(), v => v !== "baz");
for await (const value of iterable) {
  console.log(value);
}

The above example will print the following 2 lines:

baz
qux

An async predicate function also works. The following example will print the same 2 lines as the previous example:

import { dropWhile } from "./drop.ts";

async function* gen() { yield "foo"; yield "bar"; yield "baz"; yield "qux" }
const iterable = dropWhile(gen(), v => Promise.resolve(v !== "baz"));
for await (const value of iterable) {
  console.log(value);
}

A predicate function can take an index as well as the value.

import { dropWhile } from "./drop.ts";

async function* gen() { yield "foo"; yield "bar"; yield "baz"; yield "qux" }
const iterable = dropWhile(gen(), (_, i) => i % 2 === 0);
for await (const value of iterable) {
  console.log(value);
}

The above example will print the following 3 lines:

bar
baz
qux