Can one prevent Chrome causing an infinite loop when displaying alerts on the focus event, without disabling and re-enabling the event?

问题

Consider the following code. If I click in cmbMonkeys, it causes an infinite loop of alert messages in Google Chrome. My workaround for cmbPeople works fine. Does anyone know of a another way to prevent infinite loops when displaying alerts on focus or blur events, without disabling and re-enabling the event?

<html>
<head>
    <script>
        var eventHandler;

        function cmbPeople_OnFocusHandler() {
            alert("focus");
        }

        function cmbPeople_CallFocusHandler(control) {
            eventHandler = control.onfocus;
            control.onfocus = null;
            cmbPeople_OnFocusHandler();
        }

        function cmbPeople_CallBlurHandler(control) {
            control.onfocus = eventHandler;
        }

        function cmbMonkeys_FocusHandler(control) {
            alert("I like monkeys");
        }
    </script>
</head>
<body>
    monkeys <select id="cmbMonkeys" onfocus="cmbMonkeys_FocusHandler(this)"></select>
    people <select id="cmbPeople" onfocus="cmbPeople_CallFocusHandler(this)" onblur="cmbPeople_CallBlurHandler(this)"></select>
</body>
</html>

回答1:

With a simple state-handler, maybe?

var isFocus = false;
function cmbPeople_CallFocusHandler(control) {
    if(!focus){
        focus = true;
        cmbPeople_OnFocusHandler();
    }
}

function cmbPeople_CallBlurHandler(){
    isFocus = false;
}

来源：https://stackoverflow.com/questions/6151027/can-one-prevent-chrome-causing-an-infinite-loop-when-displaying-alerts-on-the-fo

标签

javascript

html

google-chrome

javascript-events

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