What types does the main pLimit function expect for its concurrency argument?

The main pLimit function accepts two types for its concurrency argument:

1. A number - An integer from 1 and up, or Number.POSITIVE_INFINITY
2. An options object - An object with a concurrency property (and optionally a rejectOnClear boolean property)

According to the TypeScript definitions [index.d.ts:L89-L90], the function signature is:

export default function pLimit(concurrency: number | Options): LimitFunction;

Where Options is defined in [index.d.ts:L91-L110] as an object containing:

• concurrency (required): a number with minimum value of 1
• rejectOnClear (optional): a boolean, defaulting to false

The implementation in [index.js:L3-L8] handles both cases:

let rejectOnClear = false;

if (typeof concurrency === 'object') {
	({concurrency, rejectOnClear = false} = concurrency);
}

The validateConcurrency function [index.js:L123-L128] ensures that the concurrency value is a positive integer or Number.POSITIVE_INFINITY.

FOLLOW_UPS:

• What validation does p-limit perform on concurrency?
• How does the rejectOnClear option change behavior?
• Can concurrency be changed after creating a limit function?