node package manager
Easy sharing. Manage teams and permissions with one click. Create a free org ยป



a helper to create getter/setter properties with validations, default values, required or not, immutable or not, configurable or not and so on... Runnable in any "modern" browsers and Node.js. Struct inherits PriProp, which provides the way to define private properties in JavaScript. Thus, you can handle private properties with Struct.

Change Log


 * When you use this library in client side scripting, load all the dependencies by the following order.
 * <script type="text/javascript" src="/path/to/PriProp.js"></script>
 * <script type="text/javascript" src="/path/to/Modifiers.js"></script>
 * <script type="text/javascript" src="/path/to/Struct.js"></script>
const Struct = require('/path/to/Struct');

/* define Constructor */
const SomeClass = (function() {
  // call Struct like this.
  const _ = Struct('id'); // _ is function with some properties.

  function SomeClass(values) {
    _.construct(this, values); // initiallize

    _(this).somePrivateValue = priv;  // set a private value (PriProp's way)

  SomeClass.prototype.somePublicMethod = function() {
    return _(this).somePrivateValue; // get a private value PriProp's way

  // define getter/setter properties
  _.defineStruct(SomeClass, {

     * property name: "name" 
     * throws an error if not string in setting a value
     * required : if it is undefined, an error is thrown after _.construct().
    name : {
      modifier: _.Modifiers.string
      required: true

     * property name : "phone"
     * the value should be string, with its length within 10 to 12,
     * and also should match the XX-XXXX-XXXX-like pattern.
     * if the validation failed, it doesn't throw an error (because of "quiet"), just set default value.
     * in this case, as the default value is not set, "undefined" is set in validation failure.
     phone : {
       modifier: _.Modifiers.every(
         _.Modifiers.string.bind({max:12, min: 10}),
         _.Modifiers.regex.bind({regex: /[0-9]{2,4}-[0-9]{2,4}-[0-9]{2,4}/})

  return SomeClass;

try {
  var obj = new SomeClass();
catch (e) {
  console.error(e.message); //  name is required, but not set.

var obj = new SomeClass({name: 'shinout'});
console.log(; // undefined