README.md

About stdlib...

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hasOwnProperty

Test if an object has a specified property.

Installation

npm install @stdlib/assert-has-own-property

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var hasOwnProp = require( '@stdlib/assert-has-own-property' );

hasOwnProp( value, property )

Returns a boolean indicating if a value has a specified property.

var value = {
    'beep': 'boop'
};

var bool = hasOwnProp( value, 'beep' );
// returns true

bool = hasOwnProp( value, 'bap' );
// returns false

Notes

• In contrast to the native Object.prototype.hasOwnProperty, this function does not throw when provided null or undefined. Instead, the function returns false.

  var bool = hasOwnProp( null, 'a' );
  // returns false
  
  bool = hasOwnProp( void 0, 'a' );
  // returns false

• Value arguments other than null or undefined are coerced to objects.

  var bool = hasOwnProp( 'beep', 'length' );
  // returns true

• Property arguments are coerced to strings.

  var value = {
      'null': false
  };
  var bool = hasOwnProp( value, null );
  // returns true
  
  value = {
      '[object Object]': false
  };
  bool = hasOwnProp( value, {} );
  // returns true

Examples

var hasOwnProp = require( '@stdlib/assert-has-own-property' );

var bool = hasOwnProp( { 'a': 'b' }, 'a' );
// returns true

bool = hasOwnProp( { 'a': 'b' }, 'c' );
// returns false

bool = hasOwnProp( { 'a': 'b' }, null );
// returns false

bool = hasOwnProp( {}, 'hasOwnProperty' );
// returns false

bool = hasOwnProp( null, 'a' );
// returns false

bool = hasOwnProp( void 0, 'a' );
// returns false

bool = hasOwnProp( { 'null': false }, null );
// returns true

bool = hasOwnProp( { '[object Object]': false }, {} );
// returns true

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See Also

• @stdlib/assert-has-property: test if an object has a specified property, either own or inherited.

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Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, 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

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.