by 1 contributor:


Access, set and clear environment variables.


var { env } = require('sdk/system/environment');

You can get the value of an environment variable, by accessing the property with the name of the desired variable:

var PATH = env.PATH;

You can check for the existence of an environment variable by checking whether a property with that variable name exists:

console.log('PATH' in env); // true
console.log('FOO' in env);  // false

You can set the value of an environment variable by setting the property:

env.FOO = 'foo';
env.PATH += ':/my/path/'

You can unset an environment variable by deleting the property:

delete env.FOO;


There is no way to enumerate existing environment variables, also env won't have any enumerable properties:

console.log(Object.keys(env)); // []

Environment variable will be unset, show up as non-existing if it's set to null, undefined or ''.

env.FOO = null;
console.log('FOO' in env);  // false
env.BAR = '';
console.log(env.BAR);       // undefined

Document Tags and Contributors

 Contributors to this page: wbamberg
 Last updated by: wbamberg,
Hide Sidebar