php variable in javascript array

Question

Why is my Javascript array empty? In a while loop I fill a variable ($btext). When I echo $btext everything is shown fine:

But if I try to fill the Javascript array nothing is printed there.

This is how I fill the variable $btext in php:

$btext .= "\"".${'name_'.$user}."\",";

Here the Javascript part:

var battletext = new Array(<? echo $btext; ?>);

If I define $btext like:

$btext = "\"Hallo\", \"Welt\"";

the Sourcecode looks like this:

<script>
var battletext = new Array("Hallo", "Welt");
</script>

Why do you think it would be empty? battletext has a length of 2.
Try $btext = array(); $btext[] = ${'name_'.$user}; echo "var battletext = ".json_encode($btext).";";

Esailija · Answer 1 · 2012-05-24 11:09:41Z

up vote 6 down vote

You should just use json encode:

$battletext = array( "Hallo", "Welt" );

html:

<script>
var battletext = <?php echo json_encode( $battletext ); ?>;
</script>

source:

<script>
var battletext = ["Hallo", "Welt"];
</script>

answered May 24 '12 at 11:09

Esailija
60.9k74892

	How can I fill the $battletext in a while loop? – Quicknation May 24 '12 at 11:17
	To explain what i like to do: I like to fill in the loop a variable ($btext) and later the JS should step through every part of the variable and show this in a textbox – Quicknation May 24 '12 at 11:20
	@Quicknation Instead of string concatenation in your loop (`$btext .=` ) declare `$btext = array()` before the loop, and inside the loop use this line: `$btext[] = ${'name_'.$user};` - then you have a PHP array of all the names, which `json_encode()` will translate to a valid Javascript array literal. As a side note, you would do better to use an array in the first place instead of variable variable names – DaveRandom May 24 '12 at 11:22
	@DaveRandom: I did it like you discribed. In the source code there is still an empty array: var battletext = <? echo json_encode($btext); ?>; if I echo $btext[1] the name is shown...??? – Quicknation May 24 '12 at 12:22
	what happens if you do `<? print_r($btext); ?>` in the same place in the code? – DaveRandom May 24 '12 at 12:28

1 Answer