Generate Array of Increasing Indices

October 2, 2018

2 min read

This is a fairly simple function to allow the easy creation of an array of an increasing order of indicies. This was useful for me to set certain indicies of a tilesheet of sprites as collidable while leaving others untouched.

new Array(length) lets you create an empty array of the specified length.

Array.from(array, mapFunction) creates a shallow copy of a given array and maps it with the provided function.

Combining the two, you can create an empty of array of the desired length and the populate a copy of that array with an increasing count of indices.

#examples

function generateArrayOfLength(length) {
  return Array.from(new Array(length), (value, index) => index);
}

generateArrayFromExclusive(5, 8);
// -> [0, 1, 2]

function generateArrayFromExclusive(low, high) {
  return Array.from(new Array(high - low), (value, index) => low + index);
}

generateArrayFromExclusive(5, 8);
// -> [5, 6, 7]

function generateArrayFromInclusive(low, high) {
  return Array.from(new Array(high - low + 1), (value, index) => low + index);
}

generateArrayFromInclusive(5, 8);
// -> [5, 6, 7, 8]

#sources

https://www.jstips.co/en/javascript/create-range-0...n-easily-using-one-line/ https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/from