Setting JavaScript variables before the opening <html> tag
I have several PHP variables that I need to transfer to JavaScript. Currently, most of my PHP code is performed as soon as the page loads, before the opening -html- tag. If I use echo to create javascript variables before the tag, will they be stored correctly? Are there reasons why I would not wa开发者_开发百科nt to do this?
You might not have any problems by assigning JS variables before the opening HTML tag, but if you don't, you're using some really non standards-compliant browsers. ;-)
General rule is that everything you define on a page should be either in the <head> or the <body>. Everything else should be counted as a mistake as it does not have defined behavior. Undefined behavior leads to badness.
If you put it as the first thing in the <head>, you should be fine though.
You should keep the variables in memory until the <script> tag is output in the HTML tag:
<?php
...
// I want to transfer: $my_var
?>
...
<html>
<head>
<script>
var php_var = <?php echo json_encode($my_var); ?>;
</script>
...
</head>
<body>
...
</body>
</html>
Use echo to create the variables inside a script tag inside the html tag. What is the problem you are having?
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