How to run Javascript from Python?

In Python, we can use the PyExecJS library or Python’s js2py library to run Javascript code. PyExecJs The library provides a consistent API to run JavaScript code from Python using a variety of JavaScript engines, including Node.js, JavaScriptCore, and Google's V8 engine. The js2py library allows you to execute JavaScript code in Python by parsing the JavaScript code and interpreting it in Python. This article will teach us how to run javascript code from Python using the PyExecJS library.

Method 1: Using the PyExecJS library

The PyExecJs library provides a simple interface to execute JavaScript code. It allows developers to seamlessly integrate JavaScript functionality into their Python applications. With PyExecJS, users can leverage the power of JavaScript libraries and frameworks without leaving the Python ecosystem.

Installing PyExecJs

Before using the PyExecJs library and we need to install it in our system using the Python package manager. To install the library type the following command in your terminal or command line. Once PyExecJS is installed, you can use the execjs module to JavaScript execute code from within Python

Pip install PyExecJs 

Using PyExecJS to run javascript from Python

JavaScript is mainly used for front-end development, while Python is usually used for back-end development. However, in some cases, the backend may require JavaScript to complete specific tasks, such as interacting with an API or performing certain calculations. Python provides many tools and libraries that allow you to run JavaScript code within Python scripts.

The Chinese translation of

Example

is:

Example

In the example below, we have some JavaScript code that defines a function to add two numbers and calls the function with parameters 2 and 3. We then use the execjs module to execute the JavaScript code and get the result by calling the eval method of the context object returned by execjs.compile. Finally, we print the results.

import execjs

# Define some JavaScript code
js_code = """
function addNumbers(a, b) {
   return a + b;
}

var result = addNumbers(2, 3);
"""

# Use execjs to execute the JavaScript code
ctx = execjs.compile(js_code)

# Get the result of the JavaScript code
result = ctx.eval('result')

# Print the result
print(result)

Output

5

Method 2: Using the js2py library

The js2py is a library that allows you to execute JavaScript code from within Python by parsing the JavaScript code and interpreting it in Python. It is written entirely in Python and does not require any external JavaScript engine to be installed.

Installation

To install the js2py library type the following command in your terminal or command line. Once js2py is installed, you can use the execjs module to execute JavaScript code from within Python

pip install js2py

The Chinese translation of

Example

is:

Example

In the below example, we define some JavaScript code that defines a function to add two numbers together and calls that function with the arguments 2 and 3. We then use the EvalJs class from the js2py library to execute the JavaScript code and get the result by calling the execute method on the context object. Finally, we print the result using a context object.

import js2py

# Define some JavaScript code
js_code = """
function addNumbers(a, b) {
   return a + b;
}

var result = addNumbers(2, 3);
"""

# Use js2py to execute the JavaScript code
context = js2py.EvalJs()
result = context.execute(js_code)

# Print the result
print(context.result)

Output

5

app

Running JavaScript code in Python can be very useful in a variety of scenarios, some of which include −

• Web scraping - Web scraping is the process of extracting data from a website. Many websites use JavaScript to dynamically update their content, which can make web crawling more challenging. Running JavaScript code in Python can help overcome this challenge, allowing you to execute JavaScript code on a web page and extract dynamically updated content.

• Server-side Web Development − Node.js is a popular JavaScript runtime built on the V8 engine that allows you to run JavaScript code on the server side. However, if you are already familiar with Python and its libraries, you may want to use Python for server-side web development. Running JavaScript code in Python can help you integrate JavaScript-based libraries and APIs into your Python-based web application.

• Testing - JavaScript is widely used for web development, while Python is widely used for testing. Running JavaScript code in Python can help you automate testing of JavaScript-based applications by executing the JavaScript code and testing its output.

• Data Science - JavaScript is not commonly used in data science, but it is used to create interactive visualizations and animations on the web. Running JavaScript code in Python can help you integrate JavaScript-based visualizations and animations into Python-based data science projects.

• Cross-platform development − JavaScript is usually used for front-end web development, while Python is usually used for back-end development and scripting. Running JavaScript code in Python can help you build cross-platform applications that use JavaScript as the front end and Python as the backend.

in conclusion

In this article, we discussed how to run javascript files from Python using Python’s PyExecJS library. These libraries provide a consistent and easy-to-use API for running JavaScript code and can be installed using pip. We can also use js2py library to run javascript code in Python. The js2py library allows you to execute JavaScript code from Python by parsing the JavaScript code and interpreting it in Python.

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