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stdlib/lib/node_modules/@stdlib/assert/instance-of at develop · stdlib-js/stdlib

instanceOf

Test whether a value has in its prototype chain a specified constructor as a prototype property.

Usage

var instanceOf = require( '@stdlib/assert/instance-of' );

instanceOf( value, constructor )

Tests whether a value has in its prototype chain a specified constructor as a prototype property.

var inherit = require( '@stdlib/utils/inherit' );

function Foo() {
    return this;
}

function Bar() {
    return this;
}
inherit( Bar, Foo );

var bar = new Bar();

var bool = instanceOf( bar, Foo );
// returns true

Notes

  • The function throws a TypeError if provided a constructor argument which is not callable.

    var bool = instanceOf( {}, null );
// throws <TypeError>

  • While the prototype of an object created using object literal notion is undefined, the function returns true when provided an object literal and the Object constructor. This maintains consistent behavior with the instanceof operator.

    var Object = require( '@stdlib/object/ctor' );

var bool = ( {} instanceof Object );
// returns true

bool = instanceOf( {}, Object );
// returns true

Examples

var Number = require( '@stdlib/number/ctor' );
var Object = require( '@stdlib/object/ctor' );
var Function = require( '@stdlib/function/ctor' );
var instanceOf = require( '@stdlib/assert/instance-of' );

var bool = instanceOf( [], Array );
// returns true

bool = instanceOf( [], Object );
// returns true

bool = instanceOf( {}, Object );
// returns true

bool = instanceOf( new Date(), Date );
// returns true

bool = instanceOf( /.*/, RegExp );
// returns true

bool = instanceOf( instanceOf, Function );
// returns true

bool = instanceOf( null, Object );
// returns false

bool = instanceOf( 5, Number );
// returns false

bool = instanceOf( '5', String );
// returns false

bool = instanceOf( void 0, Object );
// returns false

bool = instanceOf( {}, Array );
// returns false

bool = instanceOf( {}, Function );
// returns false

See Also