HTML input onfocus & onblur?

问题

ok, today I'm making a helper HTML function. It looks like this:

function Input($name,$type,$lable,$value= null){
  if (isset($value)) {
    //if (this.value=='search') this.value = ''
    echo '<label for="'. $name .'">'. $lable .'</label><input type="'.$type.'" name="'. $name .'" id="'. $name .'" value="'.$value.'" onfocus="if (this.value==\''.$value.'\') this.value = \'\' "/>';  
  }
  if (!isset($value)) {
    echo '<label for="'. $name .'">'. $lable .'</label><input type="'.$type.'" name="'. $name .'" id="'. $name .'" />'; 
  }
}

As you can see, if you insert a value it will do some JavaScript so that when I click the box, the text inside the box will disappear,

Question: How can we make it to have a value when we are not on the input? (please look at the search box on stackoverflow, however the one that is on stackoverflow doesn't come back after we are not pointing at the input box? Maybe by using onblur? Am I right?

Hope you understand what I mean.

ok becouse some of you are not getting what i mean please see

when im not clicking it.

when im clicking it.

when im not clicking it again.

it should be

when im not clicking it.

when im clicking it.

when im not clicking it again.

回答1:

You want this

<input ...
onfocus="if (this.value==this.defaultValue) this.value = ''"
onblur="if (this.value=='') this.value = this.defaultValue" />

Update: Some newer browsers will do what you want simply by adding the placeholder attribute:

<input placeholder="Please enter your name" />

Here is the PHP according to your code

echo <<<END
<label for="$name">$lable</label>
<input type="$type" name="$name" id="$name" value="$value" 
 onfocus="if (this.value==this.defaultValue) this.value = ''" 
 onblur="if (this.value=='') this.value = this.defaultValue"/>
END;

回答2:

Looking at the source for this page shows the following

<form id="search" action="/search" method="get"> 
  <div> 
     <input name="q" class="textbox" tabindex="1" 
     onfocus="if (this.value=='search') this.value = ''" 
     type="text" maxlength="80" size="28" value="search"> 
  </div>

回答3:

If I understand correctly, SO uses this line of HTML to do that effect.

<input name="q" class="textbox" tabindex="1" onfocus="if (this.value=='search') this.value = ''" type="text" maxlength="80" size="28" value="search">

Not related to your question, but you could and should replace your second if statement with an else statement.

function Input($name,$type,$lable,$value= null){
  if (isset($value)) {
    //if (this.value=='search') this.value = ''
    echo '<label for="'. $name .'">'. $lable .'</label><input type="'.$type.'" name="'. $name .'" id="'. $name .'" value="'.$value.'" onfocus="if (this.value==\''.$value.'\') this.value = \'\' "/>';  
  }
  else {
    echo '<label for="'. $name .'">'. $lable .'</label><input type="'.$type.'" name="'. $name .'" id="'. $name .'" />'; 
  }
}

Because if isset($value) returns false then you know for a fact that it isn't set since it can only return one of two values, true or false.

EDIT: Disregard this answer. It was not clear what the question was before the edit.

回答4:

Or this if you want it to change back to default no matter what text is entered...

<input ... 
onfocus="if (this.value==this.defaultValue) this.value = ''" 
onblur="if (this.value!=this.defaultValue) this.value = this.defaultValue" />

回答5:

Try this. Maybe it can help you:

<form action="/search" method="get">
<input type="text" name="q" value="Search..." onfocus="if (this.value == 'Search...') (this.value='')" onblur="if (this.value == '') (this.value='Search...')" />

来源：https://stackoverflow.com/questions/3329694/html-input-onfocus-onblur

标签

javascript

html

effects

onblur

onfocus