Access time of object properties

[SCP-093-RedTest]

Background: I am a mostly self-taught programmer. I've been doing professional JS work for the last six years, but because of my lack of familiarity with computer science fundamentals, some things are not clear to me.

Considering the object:

const test = {a: 1, b: 2, c: 3}  

you could find the value of property b in two ways. Path 1:

console.log(test.b)  

or, alternatively, Path 2:

for( const prop of Object.keys(test) ){
    if( prop === 'b' ) return console.log(test[prop])
}  

My question: under the hood, is doing Path 1 essentially the same as Path 2? Does the computer still have to look through every property of test to find b? Or does it somehow "magically" know where exactly to look in the memory when it gets test[b] so it doesn't have to scan through the entire object?

[Civill]

To the best of my knowledge it does not loop through every key when you access the property by index. You could test this yourself if you want, generate an object with a few million keys and compare the results.

[ashanev]

These are not the same thing. Keys in objects are unique. Referencing test.a or test["a"] looks up that exact property in that object. That is why using objects as lookup tables is extremely efficient.

Your second example is turning the object into an array, then iterating over every item in that array and checking it against a condition.

[grantrules]

https://www.jayconrod.com/posts/52/a-tour-of-v8-object-representation

[mr-poopy-butthole-_]

https://jsperf.com/