JSFiddle - React, Tailwind, and code Playground

JavaScript

/**
 * @param {number} num
 * @return {number[]}
 */
var countBits = function(num) {
    var arr = [0]
    var temp = [1]
    for (n = 1, range = 1000; n < range; n++) {
        arr = arr.concat(temp)
        if (arr.length > num){
        	break;
        }
        temp.push(n + 1)
    }
    arr.length = num + 1
    return arr
};


var test = countBits(5)
console.log(test)