Question

How to create a range of numbers in JavaScript

Answer 1

const range = (options) => {
  const { from = 0, step = 1, to } = options;

  if (to <= from) {
    throw Error(`"Error: from (${from}) >= to (${to})"`);
  }

  return Array.from(
    { length: Math.ceil((to - from) / step) },
    (_, i) => i * step + from
  );
};


let rng = range({ from: 1, to: 10 });

console.log(rng);



/*
run:
   
[1, 2, 3, 4, 5, 6, 7, 8, 9]
   
*/

 

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Answer 2

const n = 10;

let rng = [...Array(n).keys()];

console.log(rng);



/*
run:
   
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
   
*/

 

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Answer 3

function range(start, end) {
    if (start === end) return [start];
     
    if (start > end) {
        throw Error(`"Error: start (${start}) >= end (${end})"`);
    }
     
    return [start, ...range(start + 1, end)];
}
 
let rng = range(2, 8);
 
console.log(rng);
 
 
 
/*
run:
    
[2, 3, 4, 5, 6, 7, 8]
    
*/

 

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