npm install @stdlib/proxy-ctor

Alternatively,

• To load the package in a website via ascript tag without installation and bundlers, use theES Module available on theesm branch (seeREADME).
• If you are using Deno, visit thedeno branch (seeREADME for usage intructions).
• For use in Observable, or in browser/node environments, use theUniversal Module Definition (UMD) build available on theumd branch (seeREADME).

Thebranches.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.

varProxy=require('@stdlib/proxy-ctor');

Returns aproxy object implementing custom behavior for specified object operations.

functionget(target,property){returntarget[property]*2.0;}varhandlers={'get':get};varp=newProxy({},handlers);p.a=3.14;varv=p.a;// returns 6.28

Ahandlers argument should be anobject whose properties are functions (called "traps") which define the behavior of the proxy when performing operations. The following traps are supported:

• getPrototypeOf( target )

  • Trap forObject.getPrototypeOf(). Can be used to intercept theinstanceof operator. The method must return anobject ornull.

• setPrototypeOf( target, prototype )

  • Trap forObject.setPrototypeOf(). The method must return aboolean indicating if the prototype was successfully set.

• isExtensible( target )

  • Trap forObject.isExtensible(). The method must return aboolean.

• preventExtensions( target )

  • Trap forObject.preventExtensions(). The method must return aboolean.

• getOwnPropertyDescriptor( target, property )

  • Trap forObject.getOwnPropertyDescriptor(). The method must return anobject orundefined.

• defineProperty( target, property, descriptor )

  • Trap forObject.defineProperty(). The method must return aboolean indicating whether the operation succeeded.

• has( target, property )

  • Trap for thein operator. The method must return aboolean.

• get( target, property, receiver )

  • Trap for retrieving property values. The method can return any value.

• set( target, property, value, receiver )

  • Trap for setting property values. The method should return aboolean indicating whether assignment succeeded.

• deleteProperty( target, property )

  • Trap for thedelete operator. The method must return aboolean indicating whether operation succeeded.

• ownKeys( target )

  • Trap forObject.keys,Object.getOwnPropertyNames(), andObject.getOwnPropertySymbols(). The method must return an enumerableobject.

• apply( target, thisArg, argumentsList )

  • Trap for a function call. The method can return any value.

• construct( target, argumentsList, newTarget )

  • Trap for thenew operator. The method must return anobject.

All traps areoptional. If a trap is not defined, the default behavior is to forward the operation to the target.

This package is part ofstdlib, 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 developstdlib, see the main projectrepository.

SeeLICENSE.

Copyright © 2016-2025. The StdlibAuthors.