How to use javascript to access php variable? [duplicate]

Question

How to use javascript to access php variable? Does only one way to write code (like var a={?echo $variable})in javascript?

Recommend some books on php and javascipt(include projects)?I don't know how to use knowledge in projects?

Answer 1

Yes, you were correct.
Because PHP is executed before JavaScript, you can't change it later on, but you could do something like this:

<? $aVar = "whatever"; ?>
...
<script>
    var aVar = "<? echo $aVar; ?>"; // note the quotes! (SO's highlighter renders this incorrectly, starting a PHP block inside quotes is valid and will be recognized.)
</script>

That will send this to the client:

<script>
    var aVar = "whatever"; // note the quotes!
</script>

Answer 2

var a=<?php echo $variable; ?>

PHP runs in server and js in client side, so Iguess there is not other you can get it. OR you need to use AJAX

Answer 3

I don't see how can you do that in any other method. PHP is server side, while JS is executed on client's PC (not on the web server). Theoretically and practically it's not possible.