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Checks if the provided value is of the specified type.
- Ensure the value is not
undefinedornullusingArray.prototype.includes(). - Use
Object.prototype.constructorto compare the constructor property on the value withtypeto check if the provided value is of the specifiedtype.
const is = (type, val) => ![, null].includes(val) && val.constructor === type;is(Array, [1]); // true
is(ArrayBuffer, new ArrayBuffer()); // true
is(Map, new Map()); // true
is(RegExp, /./g); // true
is(Set, new Set()); // true
is(WeakMap, new WeakMap()); // true
is(WeakSet, new WeakSet()); // true
is(String, ''); // true
is(String, new String('')); // true
is(Number, 1); // true
is(Number, new Number(1)); // true
is(Boolean, true); // true
is(Boolean, new Boolean(true)); // trueRecommended snippets
Value is array-like
JavaScript, Type
Checks if the provided argument is array-like (i.e. is iterable).
Collection is empty
JavaScript, Type
Checks if the a value is an empty object/collection, has no enumerable properties or is any type that is not considered a collection.
Value is plain object
JavaScript, Type
Checks if the provided value is an object created by the Object constructor.