Check if function is native

by Luiz Silva

JavaScript

//função para verificar se é nativa
function isNative(object, name) {
    var aux = object[name];
    delete object[name];
    var result = object[name] == aux;
    object[name] = aux;
    return result;
}

//verifica se funciona
console.log(window.alert);
console.log(isNative(window, 'alert'));
console.log(window.alert);

console.log('----');
window.alert = function() { }

console.log(window.alert);
console.log(isNative(window, 'alert'));
console.log(window.alert);

console.log('----');
delete window.alert;

console.log(window.alert);
console.log(isNative(window, 'alert'));
console.log(window.alert);