---
title: Perl + JE
pagination_prev: demos/bigdata/index
pagination_next: solutions/input
---

import current from '/version.js';

:::warning

In a production application, it is strongly recommended to use a binding for a
C engine like [`JavaScript::Duktape`](/docs/demos/engines/duktape)

:::

JE is a pure-Perl JavaScript engine.

The [ExtendScript build](/docs/getting-started/installation/extendscript) can be
parsed and evaluated in a JE context.


## Integration Details

The engine deviates from ES3.  Modifying prototypes can fix some behavior:

```js
/* String#charCodeAt is missing */
var string = "";
for(var i = 0; i < 256; ++i) string += String.fromCharCode(i);
String.prototype.charCodeAt = function(n) {
  var result = string.indexOf(this.charAt(n));
  if(result == -1) throw this.charAt(n);
  return result;
};

/* workaround for String split bug */
Number.prototype.charCodeAt = function(n) { return this + 48; };

/* String#match bug with empty results */
String.prototype.old_match = String.prototype.match;
String.prototype.match = function(p) {
  var result = this.old_match(p);
  return (Array.isArray(result) && result.length == 0) ? null : result;
};
```

When loading the ExtendScript build, the BOM must be removed:

```perl
## Load SheetJS source
my $src = read_file('xlsx.extendscript.js', { binmode => ':raw' });
$src =~ s/^\xEF\xBB\xBF//; ## remove UTF8 BOM
my $XLSX = $je->eval($src);
```

### Reading Files

Data should be passed as Base64 strings:

```perl
use File::Slurp;
use MIME::Base64 qw( encode_base64 );

## Set up conversion method
$je->eval(<<'EOF');
function sheetjsparse(data) { try {
  return XLSX.read(String(data), {type: "base64", WTF:1});
} catch(e) { return String(e); } }
EOF

## Read file
my $raw_data = encode_base64(read_file($ARGV[0], { binmode => ':raw' }), "");

## Call method with data
$return_val = $je->method(sheetjsparse => $raw_data);
```

### Writing Files

Due to bugs in data interchange, it is strongly recommended to use a simple
format like `.fods`:

```perl
use File::Slurp;

## Set up conversion method
$je->eval(<<'EOF');
function sheetjswrite(wb) { try {
  return XLSX.write(wb, { WTF:1, bookType: "fods", type: "string" });
} catch(e) { return String(e); } }
EOF

## Generate file
my $fods = $je->method(sheetjswrite => $workbook);

## Write to filesystem
write_file("SheetJE.fods", $fods);
```

## Complete Example

:::note

This demo was tested on 2023 February 12 against JE 0.066

:::

1) Install `JE` through CPAN:

```bash
cpan install JE
```

2) Download the [ExtendScript build](/docs/getting-started/installation/extendscript):

<pre><code parentName="pre" {...{"className": "language-bash"}}>{`\
curl -LO https://cdn.sheetjs.com/xlsx-${current}/package/dist/xlsx.extendscript.js`}
</code></pre>

3) Download the demo [`SheetJE.pl`](pathname:///perl/SheetJE.pl):

```bash
curl -LO https://docs.sheetjs.com/perl/SheetJE.pl
```

4) Download a test file and run:

```bash
curl -LO https://sheetjs.com/data/cd.xls
perl SheetJE.pl cd.xls
```

After a short wait, the contents will be displayed in CSV form.  It will also
write a file `SheetJE.fods` that can be opened in LibreOffice.