JSFiddle - React, Tailwind, and code Playground

JavaScript

function num_rotations(arr){
    if(arr[0] < arr[(arr.length-1)])
        return 0;
    for(var x=0;x<(arr.length-1);x++){
        if(arr[x] > arr[(x+1)])
            return x+1;
    }
}
console.log(num_rotations([7,8,1,2,3]));