SOURCE

Function.prototype.myCall = function(cnx) {
    let context = cnx || this;
    let fn = this;
    context.fn = fn;
    let result = eval("context.fn("+arguments+")");
    delete context.fn;
    return result;
}

Function.prototype.myApply = function(cnx, arr) {
    let context = cnx || this;
    let fn = this;
    context.fn = fn;
    let result = eval("context.fn("+arr+")");
    delete context.fn;
    return result;
}

Function.prototype.myBind = function(cnx, arr) {
    let context = cnx || this;
    context.fn = this;
    let args = arr.concat();
    return function() {
        let result = eval("context.fn("+arr+")");
        delete context.fn;
        return result;
    }
}   

const numbers = [5, 6, 2, 3, 7];

const max = Math.max.myApply(null, numbers);

const maxFn = Math.max.myBind(null, numbers);

console.log(max);

console.log(maxFn());