Takes elements from the beginning of an async iterable as long as a specified condition is met. If the condition is not met, the iterable stops.

import { takeWhile } from "./take.ts";
import { count } from "./infinite.ts";

const iterable = takeWhile(count(0), v => v < 4);
for await (const value of iterable) console.log(value);

The above example will print the following 4 lines:

0
1
2
3

An async predicate function also works. The following example will print the same 4 lines as the previous example:

import { takeWhile } from "./take.ts";
import { count } from "./infinite.ts";

const iterable = takeWhile(count(0), v => Promise.resolve(v < 4));
for await (const value of iterable) console.log(value);

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

import { takeWhile } from "./take.ts";
import { count } from "./infinite.ts";

const iterable = takeWhile(count(0, 10), (_, i) => i < 4);
for await (const value of iterable) console.log(value);

The above example will print the following 4 lines:

0
10
20
30