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About stdlib...

We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.

The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!

Define Properties

NPM version Build Status Coverage Status

Define (and/or modify) object properties.

Usage

import defineProperties from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-define-properties@esm/index.mjs';

defineProperties( obj, properties )

Defines (and/or modifies) object properties.

import objectKeys from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-keys@esm/index.mjs';

var obj = {};
defineProperties( obj, {
    'foo': {
        'value': 'bar',
        'writable': false,
        'configurable': false,
        'enumerable': true
    },
    'baz': {
        'value': 13,
        'enumerable': false
    }
});

// Retrieve all enumerable keys:
var keys = objectKeys( obj );
// returns [...]

The properties parameter is an object whose own enumerable property values are descriptors for the properties to be defined or modified. A property descriptor has the following optional properties:

  • configurable: boolean indicating if property descriptor can be changed and if the property can be deleted from the provided object. Default: false.
  • enumerable: boolean indicating if the property shows up when enumerating object properties. Default: false.
  • writable: boolean indicating if the value associated with the property can be changed with an assignment operator. Default: false.
  • value: property value.
  • get: function which serves as a getter for the property, or, if no getter, undefined. When the property is accessed, a getter function is called without arguments and with the this context set to the object through which the property is accessed (which may not be the object on which the property is defined due to inheritance). The return value will be used as the property value. Default: undefined.
  • set: function which serves as a setter for the property, or, if no setter, undefined. When assigning a property value, a setter function is called with one argument (the value being assigned to the property) and with the this context set to the object through which the property is assigned. Default: undefined.

Notes

  • Property descriptors come in two flavors: data descriptors and accessor descriptors. A data descriptor is a property that has a value, which may or may not be writable. An accessor descriptor is a property described by a getter-setter function pair. A descriptor must be one of these two flavors and cannot be both.

Examples

<!DOCTYPE html>
<html lang="en">
<body>
<script type="module">

import defineProperties from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-define-properties@esm/index.mjs';

function Person( name ) {
    if ( !(this instanceof Person) ) {
        return new Person( name );
    }
    defineProperties( this, {
        'name': {
            'value': name,
            'writable': false
        },
        'greeting': {
            'get': function greet() {
                return 'Hello '+this.name;
            }
        }
    });
    return this;
}

var person = new Person( 'Simon' );

try {
    person.name = 'Peter';
} catch ( err ) {
    console.log( err.message );
}

var greeting = person.greeting;
// returns <string>

</script>
</body>
</html>

See Also

Notice

This package is part of stdlib, a standard library with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.

Community

Chat

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.