range

Create an iterable object for a number range.

Syntax

range(
  start: number,
  end: number,
  step?: number
): Iterable<number>

Parameters

• start (number): The starting value of the range
• end (number): The ending value of the range (inclusive)
• step (number, optional): Step size, defaults to 1

Return Value

• Iterable<number>: An iterable object for the number range

Examples

Basic Usage

import { range } from 'radash'

// From 0 to 5
for (const i of range(0, 5)) {
  console.log(i) // 0, 1, 2, 3, 4, 5
}

Specifying Step Size

import { range } from 'radash'

// From 0 to 10, step size 2
for (const i of range(0, 10, 2)) {
  console.log(i) // 0, 2, 4, 6, 8, 10
}

Negative Step Size

import { range } from 'radash'

// From 5 to 0, step size -1
for (const i of range(5, 0, -1)) {
  console.log(i) // 5, 4, 3, 2, 1, 0
}

Converting to Array

import { range } from 'radash'

const numbers = Array.from(range(1, 5))
// [1, 2, 3, 4, 5]

const evenNumbers = Array.from(range(0, 10, 2))
// [0, 2, 4, 6, 8, 10]

Generating Indices

import { range } from 'radash'

const items = ['apple', 'banana', 'cherry']

for (const i of range(0, items.length - 1)) {
  console.log(`${i}: ${items[i]}`)
}
// 0: apple
// 1: banana
// 2: cherry

Generating Date Ranges

import { range } from 'radash'

const startDate = new Date('2023-01-01')
const endDate = new Date('2023-01-05')

for (const i of range(0, 4)) {
  const date = new Date(startDate)
  date.setDate(startDate.getDate() + i)
  console.log(date.toISOString().split('T')[0])
}
// 2023-01-01
// 2023-01-02
// 2023-01-03
// 2023-01-04
// 2023-01-05

Generating Letters

import { range } from 'radash'

for (const i of range(65, 90)) { // ASCII codes A-Z
  console.log(String.fromCharCode(i))
}
// A, B, C, ..., Z

Generating Fibonacci Sequence

import { range } from 'radash'

const fibonacci = []
let prev = 0, current = 1

for (const i of range(0, 9)) {
  fibonacci.push(current)
  const next = prev + current
  prev = current
  current = next
}

console.log(fibonacci)
// [1, 1, 2, 3, 5, 8, 13, 21, 34, 55]

Generating Grid Coordinates

import { range } from 'radash'

const grid = []
for (const x of range(0, 2)) {
  for (const y of range(0, 2)) {
    grid.push([x, y])
  }
}

console.log(grid)
// [[0, 0], [0, 1], [0, 2], [1, 0], [1, 1], [1, 2], [2, 0], [2, 1], [2, 2]]

Handling Decimal Step Sizes

import { range } from 'radash'

for (const i of range(0, 1, 0.2)) {
  console.log(i.toFixed(1))
}
// 0.0, 0.2, 0.4, 0.6, 0.8, 1.0

Notes

1. Inclusive end value: The end value is inclusive
2. Step size: Step size can be positive or negative
3. Performance: Memory efficient, does not pre-generate all numbers
4. Infinite loops: Be careful to avoid creating infinite loop ranges

Differences from Other Functions

• range: Creates an iterable object for number ranges
• Array.from: Can convert range to array
• for...of: Can directly iterate over range

Performance

• Time Complexity: O(n), where n is the range size
• Space Complexity: O(1), does not pre-generate all numbers
• Use Cases: Loops, index generation, numerical calculations