jQuery: keyPress Backspace won't fire?

问题:

I wonder what I'm doing wrong:

$('.s').keypress(function(e) {

        switch (e.keyCode) {
            case 8:  // Backspace
                //console.log('backspace');
            case 9:  // Tab
            case 13: // Enter
            case 37: // Left
            case 38: // Up
            case 39: // Right
            case 40: // Down
            break;

            default:

            doSearch();
        }

    });

I want my doSearch() function also to be fired when I hit the Backspace key. At the moment absolutely nothing happens when I press Backspace in Chrome and Safari.

any ideas?

回答1:

Use keyup instead of keypress. This gets all the key codes when the user presses something

回答2:

I came across this myself. I used .on so it looks a bit different but I did this:

 $('#element').on('keypress', function() {
   //code to be executed
 }).on('keydown', function(e) {
   if (e.keyCode==8)
     $('element').trigger('keypress');
 });

Adding my Work Around here. I needed to delete ssn typed by user so i did this in jQuery

  $(this).bind("keydown", function (event) {
        // Allow: backspace, delete
        if (event.keyCode == 46 || event.keyCode == 8) 
        {
            var tempField = $(this).attr('name');
            var hiddenID = tempField.substr(tempField.indexOf('_') + 1);
            $('#' + hiddenID).val('');
            $(this).val('')
            return;
        }  // Allow: tab, escape, and enter
        else if (event.keyCode == 9 || event.keyCode == 27 || event.keyCode == 13 ||
        // Allow: Ctrl+A
        (event.keyCode == 65 && event.ctrlKey === true) ||
        // Allow: home, end, left, right
        (event.keyCode >= 35 && event.keyCode <= 39)) {
            // let it happen, don't do anything
            return;
        }
        else 
        {
            // Ensure that it is a number and stop the keypress
            if (event.shiftKey || (event.keyCode < 48 || event.keyCode > 57) &&       (event.keyCode < 96 || event.keyCode > 105)) 
            {
                event.preventDefault();
            }
        }
    });

回答3:

If you want to fire the event only on changes of your input use:

$('.s').bind('input', function(){
  console.log("search!");
  doSearch();
});

回答4:

According to the jQuery documentation for .keypress(), it does not catch non-printable characters, so backspace will not work on keypress, but it is caught in keydown and keyup:

The keypress event is sent to an element when the browser registers keyboard input. This is similar to the keydown event, except that modifier and non-printing keys such as Shift, Esc, and delete trigger keydown events but not keypress events. Other differences between the two events may arise depending on platform and browser. (https://api.jquery.com/keypress/)

In some instances keyup isn't desired or has other undesirable effects and keydown is sufficient, so one way to handle this is to use keydown to catch all keystrokes then set a timeout of a short interval so that the key is entered, then do processing in there after.

jQuery(el).keydown( function() { 
    var that = this; setTimeout( function(){ 
           /** Code that processes backspace, etc. **/ 
     }, 100 );  
 } );