onkeypress + onblur in javascript

问题

The onblur event in javascript is triggered when the element loses focus.

The onkeydown Occurs on an element that has the focus when a key is pressed down and occurs periodically until the key is released.

If I want to validate a date field, the onkeydown event concerns 9 and 13 (enter and tab key). But when I press the enter key, then I receive duplicate alert message. Of course in this case we have two tests, onblur and onkeydown event.

this is the html code :

<html:text      onblur="return onDateChange(this);"
        onkeydown="return onDateKeyPress(this);"/>

the onDateChange() method is :

function onDateChange(obj){
//validateField is an externatl javascript method which trigger an alert message if we have errors in date 
        if(validateField(obj,'date',dateFormat)){
        //do instructions
        }
}

and finally the onDateKeyPress() method is :

function onDateKeyPress(obj){
    if(window.event.keyCode == 9)
    {  
       if(validateField(obj,'date',dateFormat))
       {
           //do instructions
       }
    }
    if(window.event.keyCode == 13)
    {  
      if(validateField(obj,'date',dateFormat))
      { 
        //do instructions
      }
    }
}

So, the problem is to have one display alert message. Any suggestions?

回答1:

you can do it easily with jquery

$('#text_field_id').bind({
  blur: function(event) {
    if(validateField(this,'date',dateFormat)){
        //do instructions
        }
  },
  keydown: function(event) {
    if(event.keyCode == 9)
    {  
       if(validateField(this,'date',dateFormat))
       {
           //do instructions
       }
    }
    if(event.keyCode == 13)
    {  
       if(validateField(this,'date',dateFormat))
       {
           //do instructions
       }
    }

  }
});

you dont need to include onclick or onkeydown in your text element. One small question you want to execute same instructions in all cases or different instructions???? if you want to execute same instructions, lot of codes can be removed.

回答2:

In the solution above; keydownFired is true when blur is fired and the if branch of the code does nothing. so nothing happens.

If the blur has something to do other than showing alert; then the follwoing should work.

input.addEventListener('blur', function (e) { 

 doSomethingThatshldHappenAlwaysOnBLur();

    if (keydownFired) { 

      keydownFired = false 

    } else { 
        showAlert();    
  } 
})

来源：https://stackoverflow.com/questions/8446788/onkeypress-onblur-in-javascript

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javascript

jsp

javascript-events