periscopic

What is periscopic?

The 'periscopic' npm package is primarily used for calculating the potential life expectancy of individuals based on statistical data. It provides a way to estimate how many years of life are lost due to premature death, which can be a powerful tool for research and analysis in public health and social sciences.

What are periscopic's main functionalities?

Calculate Life Expectancy Loss

This feature allows the calculation of lost years of life by providing the age at death and the average life expectancy for the gender. The code sample demonstrates how to use the package to estimate how many years a male who died at age 47 has lost, given the average life expectancy.

const periscopic = require('periscopic');
const lifeExpectancyData = { male: 76, female: 81 };
const person = { gender: 'male', ageAtDeath: 47 };
const yearsLost = periscopic(person, lifeExpectancyData);
console.log(yearsLost);

Other packages similar to periscopic

life-expectancy

Similar to 'periscopic', this package provides tools for calculating life expectancy and potential years lost. However, it might offer different methodologies or additional demographic factors for more detailed analysis.

README

periscopic

Utility for analyzing scopes belonging to an ESTree-compliant AST.

API

import { analyze } from 'periscopic';

const ast = acorn.parse(`
const a = b;
console.log(a);
`);

const { map, globals, scope } = analyze(ast);

• map is a WeakMap<Node, Scope>, where the keys are the nodes of your AST that create a scope
• globals is a Map<string, Node> of all the identifiers that are referenced without being declared anywhere in the program (in this case, b and console)
• scope is the top-level Scope belonging to the program

Scope

Each Scope instance has the following properties:

• scope.block — true if the scope is created by a block statement (i.e. let, const and class are contained to it), false otherwise
• scope.parent — the parent scope object
• scope.declarations — a Map<string, Node> of all the variables declared in this scope, the node value referes to the declaration statement
• scope.initialised_declarations — a Set<string> of all the variables declared and initialised in this scope
• scope.references — a Set<string> of all the names referenced in this scope (or child scopes)

It also has two methods:

• scope.has(name) — returns true if name is declared in this scope or an ancestor scope
• scope.find_owner(name) — returns the scope object in which name is declared (or null if it is not declared)

extract_identifiers and extract_names

This package also exposes utilities for extracting the identifiers contained in a declaration or a function parameter:

import { extract_identifiers, extract_names } from 'periscopic';

const ast = acorn.parse(`
const { a, b: [c, d] = e } = opts;
`);

const lhs = ast.body[0].declarations[0].id;

extract_identifiers(lhs);
/*
[
	{ type: 'Identifier', name: 'a', start: 9, end: 10 },
	{ type: 'Identifier', name: 'c', start: 16, end: 17 },
	{ type: 'Identifier', name: 'd', start: 19, end: 20 }
]
*/

extract_names(lhs);
/*
['a', 'c', 'd']
*/

License

MIT

Changelog

4.0.0

• Switch from estree-walker to zimmerframe (#20)
• Create scope for SwitchStatement (#18)
• Expose default key in pkg.exports rather than import (#17)
• Don't treat export-from specifiers as global references (#16)