Math.random javascripts with php variable

Question

I would like to use php variable in my javascript. This is what I currently have and is working just fine:

<?php 
$test = '"test1","test2",test3"';
?>
<script type="text/javascript">
var values = [<?php echo $test; ?>],
valueToUse = values[Math.floor(Math.random() * values.length)];
alert(valueToUse);
</script>

However, if I use values that are retrieved from a database, this code will not work. Both variables contain exactly same values and are string type.

What does your JS look like after rendering the PHP code? What JS errors are you getting? — B-and-P, Mar 01 '16 at 06:14
The snippet is lacking a quotation for `test3` and should result in a syntax error in JavaScript. Also, to help avoid typos like that, consider using `$test = array('test1', 'test2', 'test3');` and `var values = ;`. ([How to pass variables and data from PHP to JavaScript?](http://stackoverflow.com/questions/23740548/how-to-pass-variables-and-data-from-php-to-javascript)) — Jonathan Lonowski, Mar 01 '16 at 06:17
It's a string because your php variable your giving to it is a string. So your resulting values array will always be [string] at which point your random number generates a number between 0 and 1 then floors it which means except for the very very rare chance you get a 1 it grabs your array at value 0 which is the only value your string. — Binvention, Mar 01 '16 at 06:53

score 0 · Answer 1 · answered Mar 01 '16 at 06:57

<?php 
$test = 'test1,test2,test3';
?>
<script type="text/javascript">
var values = <?php echo $test; ?>;
values=values.split(",");
valueToUse = values[Math.floor(Math.random() * values.length)];
alert(valueToUse);
</script>

Your problem was your test variable was a sting however if you call the JavaScript split function on a string it easily turns a , separated list into a JavaScript array

Math.random javascripts with php variable

1 Answers1