JavaScript == VS ===

Key Takeaways

you need to stop using the double equal sign there is only one instance where the double equal sign should be used and I'll be covering that at the end of this video so let's get started with what you should use instead it may sound a bit melodramatic to say to stop using the equal sign but let me back up my reasoning behind it let's just console log out here an equal statement we're just going to say 1 equal equal 1 and if we say that you'll see that that's true and of course that's going to be true it doesn't matter if we use equal equal or the more preferred triple equals both of these are going to equate to true but let's say we were comparing one equal to the string 1 what is this going to do is this true is this false it should be false because a number is not equal to a string but as you can see it prints out true over here and that's because double equal signs takes the type of the object and converts it so that they're both the same so this number 1 and this string they're going to be both converted to be equal to a number so it'll check 1 and then convert the string to a number is equal to that number 1 but if we use triple equals and we say that you now see that we get false instead of true and that's because this string of 1 is not equal to this number 1 now you may be thinking that's not really a big deal but this can cause a lot of really interesting problems so let's just console that log out here we have 0 is equal to an empty string as we both know this is definitely not true there's no way that 0 could ever equal an empty string but if we save that you'll see that it's equal to true and that's because it's converting the types of these objects before it's acquainting them to each other but if we use triple equals and we save you see that's equal to false because it does not convert the types of the objects this gives us a lot of weird bugs especially when entering empty values or for example if we check the 0 equal to false that says true even though 0 is not false and if we use equal equals you'll see it'll give us false instead of true for this statement but as I mentioned at the beginning this video there is one use case where you do want to use double equals sum times and that's when you're comparing a null for different objects but say you have an object and you want to see if that object is null so we have null or going to equal equal that to null which is obviously true and it doesn't matter if we use triple equals that'll also be true but sometimes you're going to have a null object that will actually be undefined instead of null so instead of null here we'll have undefined and that's a very common use case where you'll have undefined instead of null and that's actually equal to false null does not triple equal undefined but it does double equal undefined null and undefined are both considered the same when using double equals to compare and this in my opinion is the only use case where double equals should be used instead of triple equals the same rule of using double equals versus triple equals also applies to the not equal operator so let's put one over here we're going to just put the string of one and let's say that those are not equal to each other as we know exclamation point equal stands for not equal and if we say that we're going to get false because it's converting the values types before it is checking equal but if we put an exclamation point followed by two equal signs it is not going to convert the type and we'll see that these are actually not equal to each other as we would expect because the number one is not equal to the string one and this solves all the same bugs that we talked about earlier with empty strings in 0 0 and false and Nolan I'm defined as you see if we put in an ol on one side and we've put an undefined on this side we're going to see that these are actually not equal to each other but if we used single equal it would actually say that they are equal to each other so I hope you guys enjoyed that quick video on the differences between double equals and triple equals and JavaScript and why you should almost always use triple equals over a double equals unless you're comparing null and undefined you guys did enjoy this video make sure you check out my other JavaScript related videos linked over here and subscribe to my channel for more videos just like this thank you guys very much for watching and have a good day