docs.sheetjs.com/docz/docs/03-demos/31-engines/11_perl.md

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---
title: Perl + JE
pagination_prev: demos/cli
pagination_next: demos/clipboard
---
:::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):
```bash
curl -LO https://cdn.sheetjs.com/xlsx-latest/package/dist/xlsx.extendscript.js
```
3) Save the following to `SheetJE.pl`:
```perl title="SheetJE.pl"
use JE;
use File::Slurp;
use MIME::Base64 qw( encode_base64 );
## Initialize
say STDERR "Initializing Engine";
my $je = new JE;
$je->eval("var global = (function(){ return this; }).call(null);");
$je->eval(<<'EOF');
Number.prototype.charCodeAt = function(n) { return this + 48; };
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;
};
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;
};
EOF
## Load SheetJS source
say STDERR "Loading SheetJS Library";
my $src = read_file('xlsx.extendscript.js', { binmode => ':raw' });
$src =~ s/^\xEF\xBB\xBF//;
my $XLSX = $je->eval($src);
## 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); } }
function sheetjscsv(wb) { try {
var ws = wb.Sheets[wb.SheetNames[0]];
return XLSX.utils.sheet_to_csv(ws);
} catch(e) { return String(e); } }
function sheetjswrite(wb) { try {
return XLSX.write(wb, { WTF:1, bookType: "fods", type: "string" });
} catch(e) { return String(e); } }
EOF
## Read file
say STDERR "Parsing " . $ARGV[0];
my $raw_data = encode_base64(read_file($ARGV[0], { binmode => ':raw' }), "");
$workbook = $je->method(sheetjsparse => $raw_data);
## Convert to CSV
say STDERR "Converting to CSV";
my $csv_data = $je->method(sheetjscsv => $workbook);
print $csv_data;
## Write to SheetJE.fods
say STDERR "Writing to SheetJE.fods";
my $fods = $je->method(sheetjswrite => $workbook);
write_file("SheetJE.fods", $fods);
```
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.