JSFiddle - React, Tailwind, and code Playground

by Stepan Parunashvili

JavaScript

function firstIndexBefore(nums, n) {
	let res = -1;
  let left = 0;
  let right = nums.length - 1;
  while (left <= right) {
  	const mid = Math.trunc((right + left) / 2);
    const midN = nums[mid];
    if (midN > n) {
    	right = mid;
    } else {
    	res = mid;
      left = mid;
    }
  }
  return res;
}

console.log(expecti)