JSFiddle - React, Tailwind, and code Playground

JavaScript

a = 1;
b = [1,2,3,4];


function check(a,b){
    i = 0;        
    for (i=0;i<b.length;i++) {
        if (a == b[i]) {
             return true;
        }
    }
    return false;
}
    alert(check (a,b))