Run a JavaScript function from a php if statement

Question

I am using PHP conditions and want to know if I can run a JavaScript function without some one have to click on it using JavaScript:

if($value == 1)     
{  
    JavaScript to run the function  
}

How would I do that?

Answer 1

First of all keep in mind that your PHP code is evaluated on the server, while JavaScript runs in the browser on the client-side. These evaluations happen in different places, at different times. Therefore you cannot call a JavaScript function from PHP.

However with PHP you can render HTML and JavaScript code such that it is only rendered when your PHP condition is true. Maybe you may want to try something like this:

if($value == 1) {
   echo "<script>";
   echo "alert('This is an alert from JavaScript!');";
   echo "</script>";
} 

Answer 2

I know this thread is old but I just came across it and wanted to add my technique.

You can also echo the php variable into JavaScript and do something based on its value. I use it to place database values into js so the user can do math on the page with them

    <script>
var jsvar = <?php echo $phpvar ;?>
if (jsvar = x){ do something...}
</script>