We are required to write a JavaScript function that takes in a number and checks whether it is a Fibonacci number or not (i.e., it falls in Fibonacci series or not).
Our function should return true if the number is a Fibonacci number, false otherwise.
The code for this will be −
const num = 2584; const isFibonacci = num => { if(num === 0 || num === 1){ return true; } let prev = 1; let count = 2; let temp = 0; while(count <= num){ if(prev + count === num){ return true; }; temp = prev; prev = count; count += temp; }; return false; }; console.log(isFibonacci(num)); console.log(isFibonacci(6765)); console.log(isFibonacci(45)); console.log(isFibonacci(8767));
Following is the output on console −
true true false false