JavaScript: Check whether the provided value is of the specified type

JavaScript fundamental (ES6 Syntax): Exercise-208 with Solution

Write a JavaScript program to check whether the provided value is of the specified type.

• Ensure the value is not undefined or null using Array.prototype.includes().
• Compare the constructor property on the value with type to check if the provided value is of the specified type.

Sample Solution:

JavaScript Code:

//#Source https://bit.ly/2neWfJ2 
const is = (type, val) => ![, null].includes(val) && val.constructor === type;
console.log(is(Array, [1])); // true
console.log(is(ArrayBuffer, new ArrayBuffer()));
console.log(is(Map, new Map()));
console.log(is(RegExp, /./g));
console.log(is(Set, new Set()));
console.log(is(WeakMap, new WeakMap()));
console.log(is(WeakSet, new WeakSet()));
console.log(is(String, ''));
console.log(is(String, new String('')));
console.log(is(Number, 1));
console.log(is(Number, new Number(1)));
console.log(is(Boolean, true));
console.log(is(Boolean, new Boolean(true)));

Sample Output:

true
true
true
true
true
true
true
true
true
true
true
true
true

Flowchart:

Live Demo:

See the Pen javascript-basic-exercise-208-1 by w3resource (@w3resource) on CodePen.

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