Embed PDF JavaScript

Warning

Do NOT trust user input; always sanitize it. Although PDF JavaScript runs in a sandbox, arbitrary execution is dangerous and can lead to remote code execution vulnerabilities.

These examples use sample_template.pdf.

PDFs can execute JavaScript during interactions if supported by the viewer. PyPDFForm provides Python APIs and CLI commands to embed scripts into both the PDF document and its form fields.

In CLI examples, field-level scripts are configured in data.json and applied with update field, unless the section says otherwise.

The examples below embed a script that displays an alert when the pointer hovers over the test field:

LibraryCLI

alert.jsFile PathFile ObjectFile Content

app.alert("Hello World!");

from PyPDFForm import PdfWrapper

form = PdfWrapper("sample_template.pdf")
form.widgets["test"].on_hovered_over_javascript = "./alert.js"

form.write("output.pdf")

from PyPDFForm import PdfWrapper

form = PdfWrapper("sample_template.pdf")
form.widgets["test"].on_hovered_over_javascript = open("./alert.js")  # in practice, use a context manager

form.write("output.pdf")

from PyPDFForm import PdfWrapper

form = PdfWrapper("sample_template.pdf")
form.widgets["test"].on_hovered_over_javascript = open("./alert.js").read()  # in practice, use a context manager

form.write("output.pdf")

alert.jsdata.jsonCommand

app.alert("Hello World!");

{
    "test": {
        "on_hovered_over_javascript": "./alert.js"
    }
}

pypdfform update field sample_template.pdf -f data.json -o output.pdf

Tip

For supported Acrobat JavaScript APIs, see the Adobe JavaScript API reference.

Execute JavaScript on hover

Set on_hovered_over_javascript to run code when the pointer hovers over a field:

LibraryCLI

script.jsmain.py

this.getField("test").value = "hovered over";

from PyPDFForm import PdfWrapper

form = PdfWrapper("sample_template.pdf")
form.widgets["test"].on_hovered_over_javascript = "./script.js"

form.write("output.pdf")

script.jsdata.jsonCommand

this.getField("test").value = "hovered over";

{
    "test": {
        "on_hovered_over_javascript": "./script.js"
    }
}

pypdfform update field sample_template.pdf -f data.json -o output.pdf

Execute JavaScript when hover ends

Set on_hovered_off_javascript to run code when the pointer leaves a field:

LibraryCLI

script.jsmain.py

this.getField("test").value = "hovered off";

from PyPDFForm import PdfWrapper

form = PdfWrapper("sample_template.pdf")
form.widgets["test"].on_hovered_off_javascript = "./script.js"

form.write("output.pdf")

script.jsdata.jsonCommand

this.getField("test").value = "hovered off";

{
    "test": {
        "on_hovered_off_javascript": "./script.js"
    }
}

pypdfform update field sample_template.pdf -f data.json -o output.pdf

Execute JavaScript on mouse press

Set on_mouse_pressed_javascript to run code when a mouse button is pressed inside a field:

LibraryCLI

script.jsmain.py

this.getField("test").value = "mouse pressed";

from PyPDFForm import PdfWrapper

form = PdfWrapper("sample_template.pdf")
form.widgets["test"].on_mouse_pressed_javascript = "./script.js"

form.write("output.pdf")

script.jsdata.jsonCommand

this.getField("test").value = "mouse pressed";

{
    "test": {
        "on_mouse_pressed_javascript": "./script.js"
    }
}

pypdfform update field sample_template.pdf -f data.json -o output.pdf

Execute JavaScript on mouse release

Set on_mouse_released_javascript to run code when a mouse button is released inside a field:

LibraryCLI

script.jsmain.py

this.getField("test").value = "mouse released";

from PyPDFForm import PdfWrapper

form = PdfWrapper("sample_template.pdf")
form.widgets["test"].on_mouse_released_javascript = "./script.js"

form.write("output.pdf")

script.jsdata.jsonCommand

this.getField("test").value = "mouse released";

{
    "test": {
        "on_mouse_released_javascript": "./script.js"
    }
}

pypdfform update field sample_template.pdf -f data.json -o output.pdf

Execute JavaScript on focus

Set on_focused_javascript to run code when a field gains focus:

LibraryCLI

script.jsmain.py

this.getField("test").value = "focused";

from PyPDFForm import PdfWrapper

form = PdfWrapper("sample_template.pdf")
form.widgets["test"].on_focused_javascript = "./script.js"

form.write("output.pdf")

script.jsdata.jsonCommand

this.getField("test").value = "focused";

{
    "test": {
        "on_focused_javascript": "./script.js"
    }
}

pypdfform update field sample_template.pdf -f data.json -o output.pdf

Execute JavaScript on blur

Set on_blurred_javascript to run code when a field loses focus:

LibraryCLI

script.jsmain.py

this.getField("test").value = "not focused";

from PyPDFForm import PdfWrapper

form = PdfWrapper("sample_template.pdf")
form.widgets["test"].on_blurred_javascript = "./script.js"

form.write("output.pdf")

script.jsdata.jsonCommand

this.getField("test").value = "not focused";

{
    "test": {
        "on_blurred_javascript": "./script.js"
    }
}

pypdfform update field sample_template.pdf -f data.json -o output.pdf

Execute JavaScript on PDF open

LibraryCLI

Use PdfWrapper.on_open_javascript to set or read the script that runs when the PDF opens:

script.jsmain.py

this.getField("test").value = "opened";

from PyPDFForm import PdfWrapper

form = PdfWrapper("sample_template.pdf")
form.on_open_javascript = "./script.js"
print(form.on_open_javascript)

form.write("output.pdf")

Use update script to set document-level JavaScript that runs when the PDF opens:

script.jsCommand

this.getField("test").value = "opened";

pypdfform update script sample_template.pdf -s script.js -o output.pdf