pyjar

Python-inspired utilities for JavaScript.

Installation

Install pyjar from npm:

npm install pyjar

Then require it in your JavaScript project:

const pyjar = require("pyjar");

You can also destructure the functions you need:

const {
print,
len,
range,
enumerate,
zip,
sum,
min,
max,
sorted,
reversed,
abs,
any,
all,
keys,
values,
items,
get,
append,
extend,
pop,
isinstance,
startswith,
endswith
} = require("pyjar");

Usage

print()

A Python-style wrapper around JavaScript’s console.log().

print("Hello");
print("Value:", 42);

len()

Returns the length or size of a value.

Supports strings, arrays, Map, Set, and objects.

len([1, 2, 3]);
// 3

len("hello");

len(new Set([1, 2, 3]));

len({ name: "Alice", age: 25 });

Passing null or undefined throws a TypeError.

range()

Creates an array of numbers using Python-style range syntax.

range(5);
// [0, 1, 2, 3, 4]

range(2, 5);

range(2, 10, 2);

range(5, 0, -1);

The step value cannot be 0.

enumerate()

Creates index-value pairs from an iterable.

enumerate(["apple", "banana", "orange"]);
// [
// [0, "apple"],
// [1, "banana"],
// [2, "orange"]
// ]

A custom starting index can be provided:

enumerate(["apple", "banana"], 1);
// [
// [1, "apple"],
// [2, "banana"]
// ]

zip()

Combines multiple iterables into arrays of corresponding values.

zip(
["Alice", "Bob"],
[20, 25]
);

The result stops at the shortest iterable.

sum()

Calculates the sum of values in an iterable.

sum([1, 2, 3]);
// 6

sum([1, 2, 3], 10);

The second argument specifies the starting value.

min() and max()

Find the smallest or largest value in an iterable.

min([3, 1, 2]);
// 1

max([3, 1, 2]);

sorted()

Returns a sorted copy of an iterable without modifying the original.

sorted([3, 1, 2]);
// [1, 2, 3]

Use reverse to sort in descending order:

sorted([3, 1, 2], null, true);
// [3, 2, 1]

A key function can be supplied for custom sorting:

const users = [
{ name: "Alice", age: 30 },
{ name: "Bob", age: 20 },
{ name: "Charlie", age: 25 }
];

sorted(users, user ⇒ user.age);

reversed()

Returns a reversed copy of an iterable.

reversed([1, 2, 3]);
// [3, 2, 1]

abs()

Returns the absolute value of a number.

abs(-10);
// 10

any()

Returns true if at least one value is truthy.

any([false, false, true]);
// true

A predicate can also be provided:

any([1, 2, 3], value => value > 2);
// true

all()

Returns true if every value is truthy.

all([true, true, true]);
// true

A predicate can also be provided:

all([2, 4, 6], value => value % 2 === 0);
// true

Dictionary Helpers

keys()

Returns the keys of an object.

keys({
name: "Alice",
age: 25
});

values()

Returns the values of an object.

values({
name: "Alice",
age: 25
});

items()

Returns an object’s key-value pairs.

items({
name: "Alice",
age: 25
});

get()

Gets a property from an object and returns a default value when it does not exist.

const user = {
name: "Alice"
};

get(user, "name", "Unknown");

get(user, "age", 0);

List Helpers

append()

Appends a value to an array.

const numbers = [1, 2];

append(numbers, 3);

console.log(numbers);

The modified array is returned.

extend()

Adds multiple values to an array.

const numbers = [1, 2];

extend(numbers, [3, 4]);

console.log(numbers);

pop()

Removes and returns an item from an array.

const numbers = [1, 2, 3];

pop(numbers);

An index can be supplied:

const numbers = [10, 20, 30];

pop(numbers, 0);

Negative indexes are supported:

const numbers = [10, 20, 30];

pop(numbers, -1);

Type Checking

isinstance()

Provides Python-style type checking for common JavaScript values.

isinstance(10, "int");
// true

isinstance(10.5, "float");

isinstance(10, "number");

isinstance("hello", "str");

isinstance(true, "bool");

isinstance([1, 2], "list");

isinstance({ name: "Alice" }, "dict");

isinstance(null, "null");

isinstance(undefined, "undefined");

Supported type names:

int float number str bool list dict null undefined

For other values, isinstance() uses JavaScript’s instanceof.

String Helpers

startswith()

Checks whether a string begins with a specified prefix.

startswith("hello world", "hello");
// true

startswith("hello world", "world");

endswith()

Checks whether a string ends with a specified suffix.

endswith("hello world", "world");
// true

endswith("hello world", "hello");

Complete Example

const {
print,
range,
enumerate,
sum,
sorted,
isinstance,
startswith
} = require("pyjar");

const numbers = [5, 2, 8, 1, 3];

print("Numbers:", numbers); print("Range:", range(5)); print("Sum:", sum(numbers)); print("Sorted:", sorted(numbers));

for (const [index, value] of enumerate(numbers)) { print(index, value); }

print(isinstance(numbers, "list")); print(startswith("pyjar", "py"));

API

Function	Description
print()	Print values to the console
len()	Get the length or size of a value
range()	Generate a sequence of numbers
enumerate()	Generate index-value pairs
zip()	Combine multiple iterables
sum()	Calculate the sum of an iterable
min()	Find the minimum value
max()	Find the maximum value
sorted()	Return a sorted copy of an iterable
reversed()	Return a reversed copy of an iterable
abs()	Return the absolute value
any()	Check whether any value is truthy or matches a predicate
all()	Check whether all values are truthy or match a predicate
keys()	Get the keys of an object
values()	Get the values of an object
items()	Get the entries of an object
get()	Get an object property with a default value
append()	Append a value to an array
extend()	Extend an array with multiple values
pop()	Remove and return an array value
isinstance()	Perform Python-style type checking
startswith()	Check whether a string starts with a prefix
endswith()	Check whether a string ends with a suffix

Project Structure

The npm project currently contains the main library, package metadata, tests, and package archive. {"fallbackMarkdown":"(GitHub )","reference":{"matched_text":"","prefix":null,"start_idx":7794,"end_idx":7811,"safe_urls":["https://github.com/cloudberrypitech/pyjar"],"refs":[],"alt":"(GitHub )","prompt_text":null,"type":"grouped_webpages","items":[{"title":"GitHub - cloudberrypitech/pyjar · GitHub","url":"https://github.com/cloudberrypitech/pyjar","attribution":"GitHub","pub_date":null,"snippet":null,"thumbnail_url":"https://images.openai.com/static-rsc-1/9Ug32kFLNqnxErwTz82uzn6cjUWDSbOn9OnKqLVbz2aLElHeVgTL1HazSnOtRU46x5zOq1XM3hbwwNJte0z6OKtVKuxsl_7d4nRsDE8DsUS8TAR-9Qe7u0yWd7p_vIhVb7-nKgF4hUis1at3qz9wtQE6JMDNCVTfaq909WDiYacyL7Jc6IcsUMNON3W-jQJc","attribution_segments":null,"supporting_websites":,"refs":[{"turn_index":0,"ref_type":"view","ref_index":0}],"hue":null,"attributions":null}],"fallback_items":null,"style":null,"status":"done","error":null},"showLoginRequiredCard":false}

pyjar/
├── index.js
├── package.json
├── test.js
├── pyjar-1.0.0.tgz
└── .github/
└── workflows/

Running Tests

Run the project’s test file with Node.js:

node test.js

Using pyjar in a Project

After installing the package, import the utilities you need:

const { print, len, range } = require("pyjar");

print(len([1, 2, 3])); print(range(5));

pyjar is designed to make familiar Python-style operations available while working in JavaScript. :::{"fallbackMarkdown":"","reference":{"matched_text":" ","prefix":null,"start_idx":8350,"end_idx":8350,"safe_urls":[],"refs":[],"alt":"","prompt_text":null,"type":"sources_footnote","sources":[{"title":"GitHub - cloudberrypitech/pyjar · GitHub","url":"https://github.com/cloudberrypitech/pyjar","attribution":"GitHub"}],"has_images":false},"showLoginRequiredCard":false}