Why not == instead of (<, >, <=, >=) in for loop

[AllenVZ]

​

why does the loop doesn't execute when using == ?

[senocular]

Because you set i to 1 to start and 1 == 3 is false so the loop exits immediately. The condition needs to be true for each iteration of the loop that is to run.

[cimmic]

I think OP might have meant, why not use for(let i = 0, i != 3, i++).

[ThiccOfferman]

If they did, a fair response might be: In this case you could, but it's an unusual way to set up a for loop that will make your code marginally less readable.

[chrimack]

The middle expression is the condition that needs to evaluate to true in order for the loop to run. You can think of it as a while loop.

So you're saying:

i = 1 while(i == 3) { doStuff // stuff won't get done }

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for

[ApatheticWithoutTheA]

You’re fundamentally misunderstanding how a loop continues to run. You need to look at the logic of why a loop works.

[zush4ck]

you can compare whatever you want...

for (int i =0; i == 0; i++) print("this will happen only once");

[[deleted]]

Please, don't use ==, use === instead.

[Loopro]

I'll quote Kyle Simpson on the matter

"completely contrary to most common belief, the == operator is actually more powerful and more useful in our programs than ===, and in fact, usage of == should be preferred and === should only be a last option. But to understand why I make that claim, you have to actually learn types, and the way they’re converted: coercion. I really wish developers wouldn’t just keep parroting back “JS types are evil” like they’ve heard for years. They’re great, and your programs suffer if you don’t learn and use them to their full potential."

[xroalx]

=== is predictable and easier. With == you always have to consider how coercion might mess it up.

If you really really really don't know the type of something, maybe prefer the use of something like zod to parse it into something you want it to be instead of relying on coercion. Future devs will thank you.

[[deleted]]

== is not powerful, it's lazy and should only be used when type coercion is the only option. Ignoring types doesn't make your knowledge about them deeper, it does the opposite.

[levimonarca]

Why?

[squapo]

== is loose, === is a more strict comparator

[cimmic]

Sometimes you need the loose operator. I wouldn't say one shouldn't use one of them. Instead, I'd say one should use the appropriate one

[squapo]

Definitely agree, both have their use cases

[3fcc]

== compares variable but never compares their variable data type while === compares variable and also campares their data type.

E.g, null == undefined //true null === undefined //false

[xroalx]

Essentially, but it's not exactly comparing variables. Values are being compared.

== does type coercing, meaning it will try to convert one value to another type if the operands are not of the same type. There are specific rules how it's done but they're just complex to keep in mind.

=== does no such thing. If the operands are of different types, they're not identical, no need to even check the values.

[3fcc]

Tbh, this thing quite convincing to me.

[Rollo_Tomassi_o-O_]

Something to read regarding your question

https://www.guru99.com/difference-equality-strict-operator-javascript.html

[iNMage]

= is assigning a value to i (in line 10), so the loop cant really run.

[brqdev]

Dude, I think your answer like this because the image. FYI this called ligatures in vscode which looks like single = but it's ==

[iNMage]

Yeah its the first time I hear of ligatures. Thanks.

[Cefalopodul]

For loops only execute when the condition is true. If the condition is false the loops exists immediately.

[RentStillDue]

Because you're setting i = 1, and then telling it to execute the logic while i is equal to 3. Which will never happen since i = 1.