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add-accessors v2.0.1

Utility for adding getters and setters to classes


Circle CI npm version

This is a javascript library for adding getters, setters, and a "destroy" method that unsets member variables to a class.

Works with Node.js and CommonJS bundlers like Browserify.

npm install --save add-accessors


Examples use ES6, but ES6 is not necessary to use addAccessors. (Babel is an excellent tool to use to get ES6!)

const addAccessors = require('add-accessors');

class Foo {
  constructor(x) {
    this._x = x;
    this._destroyable = {
      destroy() {
        console.log('destroyable destroy called');
    this._bar = {
      remove() {
        console.log('bar remove called');
addAccessors(Foo.prototype, [
  {name: '_x', get: true, set: true},
  {name: '_destroyable', destroy: true},
  {name: '_bar', destroy: true, destroyMethod: 'remove'}

const foo = new Foo(42);
console.log(foo.getX()); // 42
console.log(foo.getX()); // 123

// "destroyable destroy called"
// "bar remove called"

console.log(foo.getX()); // undefined

The addAccessors function takes an object (such as a class prototype) and an array describing the member variables. Each member variable descriptor is made up of the following properties:

  • name: The name of the member variable. Must begin with an underscore.
  • get: Optional. If true, a getter is added to the object for this member. The getter is named "get" followed by the name with the underscore skipped and the first letter capitalized.
  • set: Optional. If true, a setter is added to the object for this member. It is named with similar rules to the getter.
  • destroy: Optional. If true, then when the object is destroyed, if this member variable is truthy, then its "destroy" method will be called. If the value of the member variable is an array, then the "destroy" method will be called on each of its values instead.
  • destroyMethod: Optional. If present, then this shall name the method to use to destroy the member variable instead of "destroy".

Getters and setter methods are added for the specified member variables, and a "destroy" method is added to the object which sets all of the member variables to undefined, and calls destroy methods on the values of the member variables that were set to have it called.

If the object already had a "destroy" method before addAccessors was called on it, then the new "destroy" method will call it at the end, so addAccessors will work correctly with inheritance.


Additional checks are done at run-time to make sure that addAccessors is used correctly. These checks can be disabled by setting the NODE_ENV environment variable to "production".


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