typeof === 和 typeof == 的区别

Question

What is the difference in using typeof === or typeof == or is same thing?, since both return the same value.

 function main() { var number = 10; console.log(typeof number == 'number'); // true console.log(typeof number === 'number'); // true } main();

Answer 1

The typeof operator always returns a string. The === compares both the value and the type whereas == operator only compares the value.

This means both the == and === comparators will always act the same when you have typeof and a string on two sides of them.

Answer 2

Prefer using the strict equality comparison === as is a subset of the == . The latter does type conversations like null and undefined being equal which can be surprising.

Answer 3

=== makes a strict comparison and only returns true if the compared elements have the same value and type

== compares only in terms of values, not type of data