JSFiddle - React, Tailwind, and code Playground

JavaScript

var filter = function(arr, func){
    var res = [];
    for(i = 0; i < arr.length; i++){
        if(func(arr[i] == true)){
            res.push(arr[i]);
            console.log(arr[i] + ' - true');
        }
        else{
            console.log(arr[i] + ' - false');
        }
    }
    return res;
}

var test = [1, 2, 3, 4, 5, 6, 7, 8];

var tesfun = function(num){
    if(num > 3 && num < 7){
        return true;
    }
    else{
        return false;
    }
}

filter(test, tesfun);