JSFiddle - React, Tailwind, and code Playground

by ronilan

JavaScript

function isFib(int) {

    var lastTwo = [0,1],
        result = false;

    while(int > lastTwo[1]){
        lastTwo.push( lastTwo[0] + lastTwo[1] );
        lastTwo.shift();
    }
    
    if(int === lastTwo[1]) {
        result = true;
    }

    return result;
}

function formatOutput(isFib) {
    
    var result = "IsNotFib";
    
    if (isFib) {
        result = "IsFib";  
    }
    
    return result;
}

console.log(formatOutput(isFib(8)));