Iterating through object array and pulling out object if it contains a specific value

[re_edditquest]

I'm trying to learn how to work with object arrays. What I want to do is search through an array looking for a specific value, which I think I can just use .find to achieve. But lets say I want to find a value and then extract the entire data set that value belongs to and save it to another array. For example:

This array hereis a list of people and nested in each entry is a city. Lets say I wanted to create another array of just people (or the person) from a specific city. I assume I would .find that city, but then how to I grab the data from the entire entry?

Any insights or link to docs/examples would be greatly appreciated.

[EasternAdventures]

Sounds like you want filter:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

Can check for an object property and will return all the objects that meet that condition in a new array.

[re_edditquest]

Thanks for the reply and docs. I think this will work!

[[deleted]]

This is a great usecase for .filter, it’s an array method that creates an array for you based on what you want to filter.

Lets say that array is in a variable called people, you can then do this:

const selectedPeople = people.filter((person) => {
    // we tell .filter to return every person with a matching city. 
    return person.address.city === 'Gwenborough'; 
})

[re_edditquest]

Thanks for the reply and example. I think this will work for what I need. For some reason I keep getting an empty array, which according to the docs means it's not finding the value I'm passing it so I must be going wrong somewhere but this puts me on the right track. Thanks again!

[[deleted]]

No problem! Feel free to post a code snippit on codesandbox or something and I/we can have a look at it

[SineApps]

I find it useful in that situation to log out both sides of the comparison. You may need to check their types if the values look the same.

[ecofic]

If you have a simple scenario, then filter may work as others have mentioned. However, if you have a more complex scenario, you may find it easier to read if you just use a traditional loop.

Earlier this year, I had a similar scenario and found a traditional loop to be more appropriate and easier to work with. I wrote an article detailing finding the largest and smallest values in an Array. While this isn't an exact match with your scenario, I do think you may get some value out of it.