Check if a variable is an array in JavaScript
In TypeScript or JavaScript, checking if a variable is an array can be completed in two ways.
Using the Array.isArray()
Using the native Array.isArray() method, a boolean will be returned.
1const names = ["sally", "billy", "mary"];
2const notAnArray = 'str';
3console.log(Array.isArray(names)); // true
4console.log(Array.isArray(notAnArray)); // false
Using the instanceOf operator
As an alternative option, instanceOf will yield the same results.
1const names = ["sally", "billy", "mary"];
2const notAnArray = 'str';
3console.log(names instanceof Array); // true
4console.log(notAnArray instanceof Array); // false