Add variable declarations for implicit global variable assignments.

$ npm install [--save-dev] add-variable-declarations

import addVariableDeclarations from 'add-variable-declarations';

const source = `
PI = 3.14;
radius = 8;
circumference = 2 * PI * radius;
`;

console.log(addVariableDeclarations(source).code);
// var PI = 3.14;
// var radius = 8;
// var circumference = 2 * PI * radius;

This project is used by decaffeinate to add variable declarations to converted CoffeeScript code. This project is not intended to allow you to write JavaScript without variable declarations, as I consider that a bad practice for the same reasons it's a bad practice in CoffeeScript.

Yes, but not all situations allow the use of let and const, such as when the variable binding takes advantage of hoisting. If you want let and const you can use this library in combination with esnext which will turn all eligible var declarations into let or const as appropriate.

MIT