Si vous voulez le faire sans utiliser jquery ou modenizer, vous pouvez utiliser le code ci-dessous:
(function(){
"use strict";
//shim for String's trim function..
function trim(string){
return string.trim ? string.trim() : string.replace(/^\s+|\s+$/g, "");
}
//returns whether the given element has the given class name..
function hasClassName(element, className){
//refactoring of Prototype's function..
var elClassName = element.className;
if(!elClassName)
return false;
var regex = new RegExp("(^|\\s)" + className + "(\\s|$)");
return regex.test(element.className);
}
function removeClassName(element, className){
//refactoring of Prototype's function..
var elClassName = element.className;
if(!elClassName)
return;
element.className = elClassName.replace(
new RegExp("(^|\\s+)" + className + "(\\s+|$)"), ' ');
}
function addClassName(element, className){
var elClassName = element.className;
if(elClassName)
element.className += " " + className;
else
element.className = className;
}
//strings to make event attachment x-browser..
var addEvent = document.addEventListener ?
'addEventListener' : 'attachEvent';
var eventPrefix = document.addEventListener ? '' : 'on';
//the class which is added when the placeholder is being used..
var placeHolderClassName = 'usingPlaceHolder';
//allows the given textField to use it's placeholder attribute
//as if it's functionality is supported natively..
window.placeHolder = function(textField){
//don't do anything if you get it for free..
if('placeholder' in document.createElement('input'))
return;
//don't do anything if the place holder attribute is not
//defined or is blank..
var placeHolder = textField.getAttribute('placeholder');
if(!placeHolder)
return;
//if it's just the empty string do nothing..
placeHolder = trim(placeHolder);
if(placeHolder === '')
return;
//called on blur - sets the value to the place holder if it's empty..
var onBlur = function(){
if(textField.value !== '') //a space is a valid input..
return;
textField.value = placeHolder;
addClassName(textField, placeHolderClassName);
};
//the blur event..
textField[addEvent](eventPrefix + 'blur', onBlur, false);
//the focus event - removes the place holder if required..
textField[addEvent](eventPrefix + 'focus', function(){
if(hasClassName(textField, placeHolderClassName)){
removeClassName(textField, placeHolderClassName);
textField.value = "";
}
}, false);
//the submit event on the form to which it's associated - if the
//placeholder is attached set the value to be empty..
var form = textField.form;
if(form){
form[addEvent](eventPrefix + 'submit', function(){
if(hasClassName(textField, placeHolderClassName))
textField.value = '';
}, false);
}
onBlur(); //call the onBlur to set it initially..
};
}());
Pour chaque champ de texte que vous souhaitez utiliser, vous devez l'exécuter placeHolder(HTMLInputElement), mais je suppose que vous pouvez simplement le modifier en conséquence! En outre, le faire de cette façon, plutôt que simplement sur le chargement signifie que vous pouvez le faire fonctionner pour les entrées qui ne sont pas dans le DOM lorsque la page se charge.
Notez que cela fonctionne en appliquant la classe: usingPlaceHolderà l'élément d'entrée, vous pouvez donc l'utiliser pour le styliser (par exemple, ajoutez la règle .usingPlaceHolder { color: #999; font-style: italic; }pour lui donner un meilleur aspect).