@aponica/assert-properties-js NPM

@aponica/assert-properties-js

Assert that a hash (dictionary object) contains certain properties.

This is a convenient way to assert, for example, that certain parameters or options have been provided. By default, all specified properties must be defined (an "and" check), but it is also possible to specify that a certain number of the possibilities are defined (an "or" check).

An equivalent PHP package, @aponica/assert-properies-php, is available, and should be kept synchronized with this version for consistency.

Installation

npm i @aponica/assert-properties-js

Usage

Example 1: Assert All Properties ("and")

Assert the hash (dictionary object) passed in as the first argument includes all of the property names specified by the second argument:

const fAssertProperties = require( '@aponica/assert-properties-js' );
try {
  fAssertProperties( { b: true, n: 123.456, z: 'hello' },
    [ 'b', 'n', 'z' ] );
  }
catch ( iErr ) {
  console.error( iErr );
  }

Example 2: Assert One Property ("or")

Assert the hash passed in as the first argument includes only one of the property names specified by the second argument:

const fAssertProperties = require( '@aponica/assert-properties-js' );
try {
  fAssertProperties( { n: 789.10 },
    [ 'b', 'n', 'z' ], { nMax: 1 } );
  }
catch ( iErr ) {
  console.error( iErr );
  }

Example 3: Assert Two Properties ("or") with Options

Assert the hash passed in as the first argument includes any two of the property names specified by the second argument, using JavaScript's "in" operator for comparison, and using a custom label in the error message. This example will throw an exception with the message "foo: too many properties":

const fAssertProperties = require( '@aponica/assert-properties-js' );
try {
  fAssertProperties( { b: true, n: 123.456, z: 'hello' },
    [ 'b', 'n', 'z' ], 
    { zLabel: 'foo', nMax: 2, nMin: 2, bUseIn: true } );
  }
catch ( iErr ) {
  console.error( iErr ); // foo: too many properties
  }

Example 4: Deep Assertions

Assert that the hash "foo" includes a property named "bar", and that "bar" is itself a hash containing only one of the properties "baz" or "qux":

const fAssertProperties = require( '@aponica/assert-properties-js' );
try {
  const foo = { bar: { baz: 1, qux: 2 } };
  fAssertProperties( foo, [ 'bar' ], { zLabel: 'foo' } );
  fAssertProperties( foo.bar, [ 'baz', 'qux' ], { zLabel: 'foo.bar', nMax: 1 } );
  }
catch ( iErr ) {
  console.error( iErr ); // foo.bar: too many properties
  }

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Contributing

Please contact us if you believe this package is missing important functionality that you'd like to provide.

Under the covers, the code is heavily commented and uses a form of Hungarian notation for data type guidance. If you submit a pull request, please try to maintain the (admittedly unusual) coding style, which is the product of many decades of programming experience.

@aponica/assert-properties-js v2.0.3