Reset the Alert function

Question

We use alert(text) to give an Alert in the window, there is a way to reset this function to instead of displaying this default window it displays a custom made in HTML but without losing its real function, it would just be a change of the "design" of the dialog box without losing its real functionality.

According to answers I can even orient myself, but how to program the part that returns the OK/CANCEL/NO

Like, this job of mine:

window.safeConfirm = function(params, callback) {
    if (typeof params === 'string') {
        params = {
            message: params
        };
    }
    var result = false;
    try {
        result = confirm(params.message);
    } catch (e) {
        result = true;
    }
    setTimeout(function() {
        callback(result);
    }, 10);
};

It serves to give an Alert in the form of "yes/no" dialog and perform a function according to the user’s response, its use would be something like:

safeConfirm({
    type: 'ERROR_1',
    message: 'lalalala'
}, function() {
    window.location.reload();
});  

if I reset the function as in the responses this function would not work and I would lose what I want is Alert functionality with Alert being done in HTML.. So after all, how to do?

Answer 1

You can just replace it:

/**
 * Ao invés de exibir uma janela de alerta,
 * a mensagem será exibida no console - CTRL + SHIFT + K.
 */
window.alert = function(msg){
  // faz algo
  console.log(msg);  
}

alert("StackOverflowPT");

If you want to "do something" and still maintain the behavior of alert, can do so:

/**
 * Exibe a mensagem no console mas ainda assim
 * mantém o comportamento do 'alert'.
 */
var _alert = window.alert;

window.alert = function(msg) {
  // faz algo
  console.log(msg);
  return _alert.apply(this, arguments);
};

alert("StackOverflowPT");

Answer 2

If you want to style the native window that appears when asked input to the user, or the system alert window this is not possible.

You can rewrite the function alert as @Renan suggested but not the native browser window for actions/behaviors standard. Example: http://jsfiddle.net/rsLavcm5/

This would be a major security breach and could easily harm the user if it were misused.

Answer 3

The functions alert, prompt and confirm, native to browsers, they have a behavior that is impossible to reproduce: they block the processing of any later Javascript code until they are dispensed with. That’s why prompt and confirm allow you to directly capture a return value, as in this example:

var valorDigitado = prompt('Digite um valor');

Any custom replacement (even if done using a modern HTML5 <dialog>) will be asynchronous and will depend on callbacks, as in your example and example of Sergio, and therefore could not directly replace a call to prompt or confirm, which are synchronous functions, which return a value.