Call Javascript function from PHP

mikerh9

I want to display window(using alert of Javascript). So if the data from the form is not in correct
format Javascript windows pop up. How I can call Java script function ?

if(something is false) {
//How to call java script function;
}

Roger_Ramjet

You can't. Nor do you need to. If you want to validate user input you use a javascript function in the head of the page and call it with the onSubmit event of the form. It is there that you generate the alert, and set the focus the field in error if you want to be user friendly.

Here is one I use


<html>
<head>

// my headers removed for obviouse reasons

<script language="JavaScript" type="text/JavaScript">
<!--
function validate()
{
	if (document.form.trans_id.value == "")
	{ alert ("Please enter your referance");
	document.form.trans_id.focus();
		return false;
	}
	else 
	if (document.form.bill_name.value == "")
		{ alert ("Please enter your Name");
		document.form.bill_name.focus();
		return false;
		}
		else
		if (document.form.amount.value == "")
			{ alert ("Please enter the Amount");
			document.form.amount.focus();
			return false;
			}
			else
			if (document.form.currency.value == "Select Currency")
				{ alert ("Please select a Currency");
				document.form.currency.focus();
				return false;
			} 
	else return true;

}
//-->
</script>
</head>
<body>

<FORM METHOD="POST" ACTION="https://www.etc" NAME="form" onSubmit="return validate();">

When a field is empty the function returns false so the post does not happen, an alert pops up with the mesage and the focus is set to the input box in question.

Search any javascript source and you will find a thousand variations of validation functions

Roger_Ramjet

How you validate the data depends on what it is and what you want to test for. Mine just test for data in required fields before submitting the form. What is in those fields is another matter.

sharyn

try this :

<?php
if ( this_condition_false )
{
?>
  <script language="Javascript">
    alert("Javascript Call is here");
  </script>
<?php
}
?>

This is what I am doing and it is working quite well.

sharyn

Roger_Ramjet

Yes Sharyn. And it still requires a call to the server. If the only way to validate the input is to query the db then, yes, you have to pass the rubbish to the target script. But if you want to ensure that there is actually something there to validate in the first place, and that it is the correct data type etc, then a javascript function is the answer.

Please understand, validating user input before submition to the server is the correct way to do it. Anyone who tells you different is just telling you that they can't handle client-side programming. This is not something special to web apps, it applies to any client-server app in any environment.

(God there are just too many amateurs in this web environment)

sharyn

Roger Ramjet,

I was answering his direct question of how to call a javascript funtion in php.

I want to display window(using alert of Javascript). So if the data from the form is not in correct
format Javascript windows pop up. How I can call Java script function ?

mikerh9 wants to display a window with a javascript alert. He asked how to call a javascript function. He is not asking a question on validation of data. So that's all I answered. I'm sure if he wants to know about data validation, you have done a great job of answering that for him :-)

Between all of us, I hope he gets his answer :-D

Roger_Ramjet

Yes he is. He is asking how to tell the user that the input is missing or is rubbish,

"So if the data from the form is not in correct
format Javascript windows pop up."

If he just wanted to know how to pass a message to the user he would have asked for that.

You have just reinforced my comment:

"Anyone who tells you different is just telling you that they can't handle client-side programming."

Sorry!