Jika Anda ingin melakukannya tanpa menggunakan jquery atau modenizer Anda dapat menggunakan kode di bawah ini:
(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..
};
}());
Untuk setiap bidang teks yang ingin Anda gunakan untuk Anda perlu menjalankan placeHolder(HTMLInputElement), tapi saya kira Anda bisa mengubahnya sesuai! Selain itu, melakukannya dengan cara ini, bukan hanya saat memuat berarti Anda dapat membuatnya berfungsi untuk input yang tidak ada di DOM saat laman dimuat.
Perhatikan, bahwa ini berfungsi dengan menerapkan class: usingPlaceHolderke elemen input, sehingga Anda dapat menggunakan ini untuk gaya itu (misalnya menambahkan aturan .usingPlaceHolder { color: #999; font-style: italic; }untuk membuatnya terlihat lebih baik).