How to compare two regexps?

Question

Why do

console.log(/a/ == /a/); 

and

var regexp1 = /a/; var regexp2 = /a/; console.log(regexp1 == regexp2); 

both return false?

Answer 1

Try this:

String(regexp1) === String(regexp2)) 

You are getting false because those two are different objects.

Answer 2

"Problem":

regex is an object- a reference type, so the comparsion is done by reference, and those are two different objects.

console.log(typeof /a/); // "object" 

If both operands are objects, then JavaScript compares internal references which are equal when operands refer to the same object in memory.

MDN

Solution:

​var a = /a/; var b = /a/; console.log(​​​a.toString() === b.toString()); // true! yessss! 

Live DEMO

Another "hack" to force the toString() on the regexes is:

console.log(a + "" === b + "");​