Chai Type-Detect

Methods

We can start using type-detect by simply requiring it using the below line of code.

var type = require('type-detect');

As already mentioned, type-detect can be used to assert different entities quickly and effectively. Let’s see some examples.

Array 

assert(type([]) === 'Array');
assert(type(new Array()) === 'Array');

Function 

assert(type(function () {}) === 'function');

Date 

assert(type(new Date) === 'Date');

Regexp 

assert(type(/a-z/gi) === 'RegExp');
assert(type(new RegExp('a-z')) === 'RegExp');

Arguments 

(function () {
    assert(type(arguments) === 'Arguments');
 })();

Number 

assert(type(3) === 'number');
assert(type(3.14) === 'number');
assert(type(-25) === 'number');
assert(type(-5.64) === 'number');
assert(type(Infinity) === 'number');
assert(type(NaN) === 'number');
assert(type(new Number(48)) === 'Number');

String 

assert(type('welcome to Coding Ninjas ') === 'string');
assert(type(new String('Coding is Fun!')) === 'String');

Undefined

assert(type(undefined) === 'undefined');
assert(type(null) !== 'undefined');

Null 

assert(type(null) === 'null');
assert(type(undefined) !== 'null');

Object

var Noop = function () {};
assert(type({}) === 'Object');
assert(type(Noop) !== 'Object');
assert(type(new Noop) === 'Object');
assert(type(new Object) === 'Object');

ECMA6 Types

assert(type(new Map() === 'Map');
assert(type(new WeakMap()) === 'WeakMap');
assert(type(new Set()) === 'Set');
assert(type(new WeakSet()) === 'WeakSet');
assert(type(Symbol()) === 'symbol');
assert(type(new Promise(callback) === 'Promise');
assert(type(new Int8Array()) === 'Int8Array');
assert(type(new Uint8Array()) === 'Uint8Array');
assert(type(new UInt8ClampedArray()) === 'Uint8ClampedArray');
assert(type(new Int16Array()) === 'Int16Array');
assert(type(new Uint16Array()) === 'Uint16Array');
assert(type(new Int32Array()) === 'Int32Array');
assert(type(new UInt32Array()) === 'Uint32Array');
assert(type(new Float32Array()) === 'Float32Array');
assert(type(new Float64Array()) === 'Float64Array');
assert(type(new ArrayBuffer()) === 'ArrayBuffer');
assert(type(new DataView(arrayBuffer)) === 'DataView');

FAQs

1. What is the difference between Mocha and Chai?
Ans: Mocha is a widely used JavaScript test framework for Node.js. Chai is a BDD / TDD assertion library for Node.js and the browser that can be paired with any JavaScript testing framework.
 

2. What is the assertion with Chai?
Ans: Assertion with Chai provides natural language assertions, expressive and readable style. The expect interface provides a function for assertion.
 

3. What is the use of the @Chai assertion library?
Ans: Chai assertion library is an external javascript library used to write assertions. Compared to what we write directly in javascript, this assertion library needs less time & effort and is easy to use.
 

4. How to test a function in Chai with JavaScript?

Ans: You have to import the validator.js file to our test file in order to access the function being tested.

Key Takeaways

In this article, we have extensively discussed Type-Detect in Chai.

We have learned:

• Need of type-detect in Chai.
• Shortcomings of typeOf and Object.prototype.toString() and how type-detect overcomes these shortcomings.
• Use type-detect to assert functions, string, number, null, objects, arguments, date, ECMA6 Types, etc.

We hope that this blog has helped you enhance your knowledge regarding Chai Type-Detect and if you would like to learn more, check out our articles on Running Mocha tests in browsers Mocha Assertions. Do upvote our blog to help other ninjas grow.

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