I've Heard Global Variables Are Bad, What Alternative Solution Should I Use?

Question

I\'ve read all over the place that global variables are bad and alternatives should be used. In Javascript specifically, what solution should I choose.

I\'m thinking

Answer 1

Using global variables is generaly speaking a bad practice, regardless of the language of choice. They are not even (easily) allowed to use when at strict mode, which I highly recommend.

Consider this piece of code I found:

if (typeof session != 'undefined' && !data.cart.request_status)
  data.input_definitions.passengers =
    inflate_passenger(session, data.input_definitions.passengers);

I needed to turn around and ask a felow programmer where did this session variable came from, as no code search showed up where was set.

I turned out another package from the company sets the global variable. Code it's like a joke: if you need to explain it it's probably not that good.

Workaround using ES6:

If at Node, use import or require to bring the desired stuff into lexical scope, don't let people touch your global environment without you knowing it.

import {Sesssion} from 'api-core';
const Session = require('api-core').session;

If you are at the frontend delivering code for the browser you can't use import unless you transpile your ES6 code using Babel.

Example transpiling using Gulp.js:

// $ npm install --save-dev gulp-babel babel-preset-es2015

// gulpfile.js
const gulp  = require('gulp');
const babel = require('gulp-babel');

gulp.task('transpile', () => {
  return gulp.src('src/app.js')
    .pipe(babel({presets: ['es2015']}))
    .pipe(gulp.dest('dist'));
});

// $ gulp transpile

Legacy workaround:

When using ES6 features is not an option the only workaround to using a bunch of global variables, is using only one, and have hope:

// scripts/app.js
var MyApp = {
  globals: {
    foo: "bar",
    fizz: "buzz"
  }
};