Whats the different between two (`==`) and three (`===`) equal signs?

FAQ JavaScript FAQ
,
23

Thanks! This article helps!

1 Like
24

It’ll be either because both have to be in common type before comparison. That doesn’t mean a or b looses it’s datatype . The conversion is only to effect symmetric comparison. Have a look at this link for more details regarding equality algorithms
developer::mozilla::Equality_comparisons_and_sameness

25

Thanks and I am glad it was helpful.

26

== compares the values but the === compares the types. in this case one is a number and the other a string

27

Welcome to the forums!

In this very simplified explanation, I’d just like to note that === compares both type and values, not just data type.

2 Likes
28

Hi. I don’t know if this is related to this forum, but why are there parentheses around the comparison statement in the example on slide 4/11 in beginner JavaScript, Conditional Statements lessons?
This was the example:
if (hungerLevel > 7) { console.log(‘Time to eat!’); }
I wrote the statement without parentheses.

29

The correct syntax for conditional statements in JS is:

if (condition1) {
  doThis();
} else if (condition2) {
  doThat();
} else {
  doThisThat();
}
2 Likes
30

This was exactly what I needed!

31

Wow that was just really helpful. Thanks for sharing it. :smiling_face_with_three_hearts: :heart:

32

when you use == operator you wanna say if the values of operand(both side) were equal , return true
no matter their type is equal or not . so this expression "1" == 1 would be true .
but in some cases we want to check if the values and the types were equal , then return true .
so "1" === 1 would be false . and 1 === 1 would be true

more examples :

console.log(1 == '1')  // true 
console.log(""==0)  // true . because string with no value always equal to 0
1 Like
33

So this means that the === compares both the variable, as well as the data type?

1 Like
34

If by variable you mean value, yes.

1 Like
37

Thanks much, perfectly explained!

38

This article is extremely helpfull and easy to understand, thanks for sharing!

40

I think that is good idea to write in English, otherwise we will not be able to understand you and help you.

1 Like
43

Can you please explain why 1 == true is true?

console.log(1 == true) // output: true

44

0 and 1 are type ‘number’ but in a Boolean expression, 0 casts to false and 1 casts to true

1 Like
45

It has also to do with the double == as opposed to triple ===, the latter of which is strict while the other is loose and coerces a boolean from the numbers.

1 == true     //  true    =>  coercive

1 === true    //  false   =>  non-coercive
2 Likes
46

Great. Thanks! Awesome explanation.

47

Really not that hard, but some mystery makes us demotivate! thank you for so helpful info :blush: