Deep JavaScript Foundations, v3

Double Equals Summary

Kyle Simpson

Kyle Simpson

You Don't Know JS
Deep JavaScript Foundations, v3

Check out a free preview of the full Deep JavaScript Foundations, v3 course

The "Double Equals Summary" Lesson is part of the full, Deep JavaScript Foundations, v3 course featured in this preview video. Here's what you'd learn in this lesson:

Kyle gives a summary of what double equals does when it is used in a program.


Transcript from the "Double Equals Summary" Lesson

>> Kyle Simpson: Let me summarize how double equals works. This is summary of the algorithm, you can read the algorithm but it's summary. If the types of the same it's just gonna use triple equals. If either of them both of them are no or undefined, they are equal. If there are non primitives involved in the comparison, they are always gonna become primitive first.

And then once you have primitives prefer to number.
>> Kyle Simpson: And I'm just optimistic enough to believe that every developer from the junior developer with two weeks of experience in JavaScript, up to the experienced developer with 20 plus years, can understand a fairly straightforward system like that. And by understanding it, avoid the places where it can be problematic.

>> Kyle Simpson: So what are those problematic cases? Many of these are ones we've already seen, but let's talk about the corner cases, we gotta talk about them so that we can avoid them.

Learn Straight from the Experts Who Shape the Modern Web

  • In-depth Courses
  • Industry Leading Experts
  • Learning Paths
  • Live Interactive Workshops
Get Unlimited Access Now