range

Generates an array of numbers from start (inclusive) to end (exclusive), incrementing by step. If step is omitted, it defaults to 1 when start <= end and -1 when start > end.

Try it

Import

import { range } from "1o1-utils";

import { range } from "1o1-utils/range";

Signature

function range({ start, end, step }: RangeParams): number[]

Parameters

Name	Type	Required	Description
start	number	No	The starting value of the sequence (default 0)
end	number	Yes	The end value of the sequence (exclusive)
step	number	No	The increment between values (default 1, or -1 when start > end)

Returns

number[] — An array of numbers from start to end stepping by step.

Examples

range({ end: 5 });
// => [0, 1, 2, 3, 4]

range({ start: 1, end: 5 });
// => [1, 2, 3, 4]

range({ start: 0, end: 10, step: 2 });
// => [0, 2, 4, 6, 8]

range({ start: 5, end: 0, step: -1 });
// => [5, 4, 3, 2, 1]

range({ start: 5, end: 0 });
// => [5, 4, 3, 2, 1]

Edge Cases

• Throws if start, end, or step is not a finite number (rejects NaN, Infinity, -Infinity).
• Throws if step is 0.
• end is exclusive — it is never included in the output.
• When start === end, returns an empty array.
• When step is omitted and start > end, the step defaults to -1.
• When the sign of step does not move from start toward end (e.g. start: 0, end: 5, step: -1), an empty array is returned.
• Non-integer step values are supported (e.g. step: 0.25).

Also known as

range, sequence, list, numbers, interval, arange

Prompt suggestion

I'm using 1o1-utils (npm: https://www.npmjs.com/package/1o1-utils, GitHub: https://github.com/pedrotroccoli/1o1-utils, LLM context: https://pedrotroccoli.github.io/1o1-utils/llms.txt). Show me how to use range to generate a sequence of numbers with a custom step.