setTimeout 内的 window.open 不执行操作

Question

Why does this call to setTimeout show the alert box but does not do the call to window.open? If I remove the alert, it doesn't do the window.open either.

    // Pause first then open window
    function pause_first (url) {
        alert (url);
        var external_window = window.open(url,'_blank'); 
        external_window.focus();
    }

    var pause_ret = setTimeout( function() { pause_first(url); }, 1000);

Answer 1

Most likely, because your browser considers it to be a non-user-triggered popup … so it blocks it.