esprima

library4.0.1pypypi✓ verified 86d ago

Esprima Python is a Python port of the Esprima ECMAScript parser. It provides an ECMAScript (JavaScript) parsing infrastructure for multipurpose analysis in Python, generating a syntax tree that adheres to the SpiderMonkey AST format. The current version is 4.0.1, with releases typically following updates to the upstream JavaScript Esprima project or significant internal Python improvements.

serialization

pip install esprima

github ↗package ↗

INSTALL

IMPORT

SIG · ESPRIMA

esprima

serializationpythonv4.0.1

Install

3.5s avg

Import

2062ms

Disk

17MB

Pass rate

10/ 10

Env Coverage10 / 10

glibc

3.9–3.13

musl

3.9–3.13

Install & Compatibility

Where this runs

tested against v4.0.1 · pip install

no network on importno background threads

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

py 3.10–3.920 runs

installs and imports cleanly · install 0.0s · import 2.175s · 19.7MB

glibc

py 3.10–3.920 runs

installs and imports cleanly · install 3.5s · import 1.950s · 20MB

17MB installed

● package 17MB

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

parse

✓ from esprima import parse

The primary function to parse JavaScript/ECMAScript code.

EsprimaException

✓ from esprima.error import EsprimaException

For handling parsing errors.

This quickstart demonstrates parsing a simple JavaScript string using `esprima.parse()` and then converting the resulting Abstract Syntax Tree (AST) object to a Python dictionary for inspection. It also shows how to catch parsing-specific exceptions.

import esprima js_code = "var answer = 42; console.log(answer);" try: # Parse the JavaScript code tree = esprima.parse(js_code, options={'loc': True, 'range': True}) # The 'tree' object is an AST. It can be converted to a dictionary. ast_dict = tree.to_dict() # Print a part of the AST (e.g., the first statement's type) if ast_dict and 'body' in ast_dict and len(ast_dict['body']) > 0: print(f"Parsed statement type: {ast_dict['body'][0]['type']}") # Example of accessing tokens (if options={'tokens': True} was used) # tokens = esprima.tokenize(js_code) # print(f"First token: {tokens[0].to_dict()}") except esprima.error.EsprimaException as e: print(f"Parsing error: {e}")

Debug

Known issues

breakingMajor API changes occurred between version 3.x and 4.x. If upgrading from an older major version, review the GitHub README for updated usage patterns. Direct migration without code changes is unlikely to work.

fix

Consult the `esprima-python` GitHub repository's README and changelog for detailed API changes when upgrading from Esprima Python 3.x to 4.x.

affects: 3.x to 4.x

breakingThe `AST.to_json()` method was removed in version 4.0.0. Use `AST.to_dict()` instead for converting the AST object to a Python dictionary, which can then be serialized to JSON using Python's `json` module if needed.

fix

Replace calls to `ast_object.to_json()` with `ast_object.to_dict()`. If JSON output is required, use `json.dumps(ast_object.to_dict())`.

affects: >=4.0.0

gotchaEsprima Python generates an AST that conforms to the SpiderMonkey Parser API's AST format for ECMAScript (JavaScript). This means the structure and node types in the resulting AST (e.g., from `tree.to_dict()`) will reflect JavaScript syntax, not Python's native AST or common Pythonic conventions. Users familiar with Python's `ast` module might find the structure different.

fix

When working with the AST, refer to the SpiderMonkey Parser API documentation or `esprima-python` examples to understand the expected node types and properties. Do not expect a Python-native AST structure.

affects: All versions

Errors

Common errors & fixes

esprima.error_handler.Error: Line X: Unexpected token

The JavaScript code contains ES Module syntax (e.g., `import` or `export` statements) but is being parsed using `parseScript()` instead of `parseModule()`.

fix

Use `esprima.parseModule(code)` instead of `esprima.parseScript(code)` to parse JavaScript modules.

esprima.error_handler.Error: Line X: Unexpected token

The JavaScript code includes JSX syntax, but the `jsx` parsing option is not enabled.

fix

Pass `{"jsx": True}` in the options dictionary to enable JSX parsing: `esprima.parseModule(code, {"jsx": True})` or `esprima.parseScript(code, {"jsx": True})`. Note that `esprima-python` (version 4.0.1) may not fully support all modern JSX features, such as React fragments (`<></>`).

ModuleNotFoundError: No module named 'esprima'

The `esprima` Python package is not installed in the current Python environment.

fix

Install the package using pip: `pip install esprima`.

esprima.error_handler.Error: Line X: Unexpected token (

An anonymous function declaration (e.g., `function () {}`) is being parsed as a statement, but `esprima` expects a named function declaration in that context.

fix

Wrap the anonymous function in parentheses to make it a function expression: `esprima.parseScript('(function () {})')`.

Upgrade

Version history

4.0.1latest on PyPI · released Aug 24, 2018

Audit

Dependencies

No dependency data recorded yet.

Agent activity

14 hits · last 30 days

node

Resources

githubhttps://github.com/Kronuz/esprima-python ↗

packagehttps://pypi.org/project/esprima/ ↗