按退格键时禁用向后导航，允许在字段中退格

Question

How can I modify this:

<script type="text/javascript">
    document.onkeydown = function(event) {
        if (event.keyCode === 8) {
            event.preventDefault();
        }
    };
</script>

To allow the user to backspace in form fields on a page, but prevent them from navigating backwards by mistake?

Answer 1

Testing the current.target to see if it's an input or not:

document.onkeydown = function(event) {
    var key = event.keyCode || event.which,
        nodeName = event.target.nodeName.toLowerCase();

    if (key === 8 && nodeName !== 'input') {
        alert('that\'s a nono');
        event.preventDefault();
    }
};

Also note the event.which to support older browsers. But that's completely up to you of course.

DEMO

Answer 2

You can also add other input fields like "textarea", "div", etc. depending on your requirements.

 document.onkeydown = function(event) { nodeName = event.target.nodeName.toLowerCase(); if ( (event.keyCode === 8 || event.which=== 8 ) && nodeName !== 'input') { event.preventDefault(); } };