Data::JavaScript(3) Dump perl data structures into JavaScript code


use Data::JavaScript; # Use defaults

@code = jsdump('my_array', $array_ref); # Return array for formatting
$code = jsdump('my_object', $hash_ref); # Return convenient string
$html = hjsdump('my_stuff', $reference); # Convenience wrapper


This module is mainly intended for CGI programming, when a perl script generates a page with client side JavaScript code that needs access to structures created on the server.

It works by creating one line of JavaScript code per datum. Therefore, structures cannot be created anonymously and need to be assigned to variables. However, this format enables dumping large structures.

The module can output code for different versions of JavaScript. It currently supports 1.1, 1.3 and you specify the version on the "use" line like so:

  use Data::JavaScript {JS=>1.3};          # The new default
  use Data::JavaScript {JS=>1.1};          # Old (pre module v1.10) format

JavaScript 1.3 contains support for UTF-8 and a native "undefined" datatype. Earlier versions support neither, and will default to an empty string '' for undefined values. You may define your own default---for either version---at compile time by supplying the default value on the "use" line:

  use Data::JavaScript {JS=>1.1, UNDEF=>'null'};

Other useful values might be 0, "null", or "NaN".


In addition, althought the module no longer uses Exporter, it heeds its import conventions; "qw(:all"), "()", etc.
jsdump('name', \$reference, [$undef]);
The first argument is required, the name of JavaScript object to create.

The second argument is required, a hashref or arrayref. Structures can be nested, circular referrencing is supported (experimentally).

The third argument is optional, a scalar whose value is to be used en lieu of undefined values when dumping a structure.

When called in list context, the function returns a list of lines. In scalar context, it returns a string.

hjsdump('name', \$reference, [$undef]);
hjsdump is identical to jsdump except that it wraps the content in script tags.


This function escapes non-printable and Unicode characters (where possible) to promote playing nice with others.


Previously, the module eval'd any data it received that looked like a number; read: real, hexadecimal, octal, or engineering notations. It now passes all non-decimal values through as strings. You will need to "eval" on the client or server side if you wish to use other notations as numbers. This is meant to protect people who store ZIP codes with leading 0's.

Unicode support requires perl 5.8 or later. Older perls will gleefully escape the non-printable portions of any UTF-8 they are fed, likely munging it in the process as far as JavaScript is concerned. If this turns out to be a problem and there is sufficient interest it may be possible to hack-in UTF-8 escaping for older perls.


  • Thou shalt not claim ownership of unmodified materials.
  • Thou shalt not claim whole ownership of modified materials.
  • Thou shalt grant the indemnity of the provider of materials.
  • Thou shalt use and dispense freely without other restrictions.

Or if you truly insist, you may use and distribute this under ther terms of Perl itself (GPL and/or Artistic License).


Maintained by Jerrad Pierce <[email protected]>

Created by Ariel Brosh <schop>. Inspired by JavaScript support.