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which-builtin-type
Advanced tools
What is the type of this builtin JavaScript value? Works cross-realm, without instanceof
, and can not be fooled by a constructor
property.
var whichBuiltinType = require('which-builtin-type');
var assert = require('assert');
assert.equal(undefined, whichBuiltinType(undefined));
assert.equal(null, whichBuiltinType(null));
assert.equal('Boolean', whichBuiltinType(false));
assert.equal('Boolean', whichBuiltinType(true));
assert.equal('Array', whichBuiltinType([]));
assert.equal('Object', whichBuiltinType({}));
assert.equal('RegExp', whichBuiltinType(/a/g));
assert.equal('RegExp', whichBuiltinType(new RegExp('a', 'g')));
assert.equal('Date', whichBuiltinType(new Date()));
assert.equal('Number', whichBuiltinType(42));
assert.equal('Number', whichBuiltinType(NaN));
assert.equal('Number', whichBuiltinType(Infinity));
assert.equal('Number', whichBuiltinType(new Number(42)));
assert.equal('String', whichBuiltinType('foo'));
assert.equal('String', whichBuiltinType(Object('foo')));
assert.equal('Function', whichBuiltinType(function () {}));
assert.equal('GeneratorFunction', whichBuiltinType(function* () {}));
assert.equal('Function', whichBuiltinType(x => x * x));
assert.equal('Array', whichBuiltinType([]));
assert.equal('Int8Array', whichBuiltinType(new Int8Array()));
assert.equal('Uint8Array', whichBuiltinType(new Uint8Array()));
assert.equal('Uint8ClampedArray', whichBuiltinType(new Uint8ClampedArray()));
assert.equal('Int16Array', whichBuiltinType(new Int16Array()));
assert.equal('Uint16Array', whichBuiltinType(new Uint16Array()));
assert.equal('Int32Array', whichBuiltinType(new Int32Array()));
assert.equal('Uint32Array', whichBuiltinType(new Uint32Array()));
assert.equal('Float32Array', whichBuiltinType(new Float32Array()));
assert.equal('Float64Array', whichBuiltinType(new Float64Array()));
assert.equal('BigInt64Array', whichBuiltinType(new BigInt64Array()));
assert.equal('BigUint64Array', whichBuiltinType(new BigUint64Array()));
Simply clone the repo, npm install
, and run npm test
v1.2.1 - 2024-12-12
8305bf9
67140db
@arethetypeswrong/cli
, @ljharb/tsconfig
, @types/function.prototype.name
, @types/tape
, has-symbols
5adff02
call-bind
, is-date-object
, is-regex
, which-boxed-primitive
87922d3
call-bound
directly 8f633bc
is-regex
, which-typed-array
a912742
FAQs
What is the type of this builtin JS value?
The npm package which-builtin-type receives a total of 22,066,842 weekly downloads. As such, which-builtin-type popularity was classified as popular.
We found that which-builtin-type demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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