JSFiddle - React, Tailwind, and code Playground

JavaScript

var value = [100, 90, 100, 80];
lowestGrade(value);

function lowestGrade (value) 
{
    var lowest;
    for(var i = 0, cnt = value.length; i<cnt; i++){
        if(typeof lowest === 'undefined') {
           lowest = value[i]
        } else {
            if(value[i] < lowest){
                lowest = value[i];
            }
        }
    }
    
    console.log(lowest);
}