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JavaScript JavaScript Loops, Arrays and Objects Tracking Data Using Objects The Build an Object Challenge, Part 2 Solution

Posted by john larson
john larson
16,594 Points

how would I access "keys" in this scenario? (using a for loop, not a for in)

//if this is the array
var family = [
    {
        title: "Derblin Prime",
        position: "Matriarch",
        name: "Dionne",
        subjugation: "Supreme"
    }
    ];

var html = "";
var i;
//and this is the loop
for(i = 0; i < family.length; i += 1){
    html+= "<h3>" + family[i].title + "</h3>";
}

//I understand that family[i].title accesses the value
//how would I access the key?
john larson
john larson
16,594 Points

I get that the "for loop" is related to arrays, and the "for in" to objects. I'm just curious about the possibilities because in this video Dave was showing us the object within the array, but we only accessed the value, not the key.

3 Answers

Jennifer Nordell
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STAFF
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Jennifer Nordell
Treehouse Teacher
Jennifer Nordell
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Jennifer Nordell
Treehouse Teacher

You could use this line to return an array of the keys.

console.log(Object.keys(family[0]));

Try that one and see if it gives you the output you're looking for! :sparkles:

john larson
john larson
16,594 Points

Thanks Jennifer, that outputs the information to the console. I'm trying to picture how I would incorporate that into the current code or is there a way to access both keys and values in an array/object combination and print to the page? Also that code looks like maybe a predefined function?

john larson
john larson
16,594 Points

never mind, I think I got it. Thank you so much. Still wondering about Object.keys though. If that's what it was meant to do or if it was kind of tweek or hack?

john larson
john larson
16,594 Points

I got it to do something pretty close to what I was looking for. I inserted as the top line in the loop so above each set of values it print on top, kinda like a header.
fun. Thanks again :D

var html = "";
var i;

for(i = 0; i < family.length; i += 1){

    html+= Object.keys(family[0]) + "<br>"
    +   "<h3>" + family[i].title + "</h3>"
    +   "<p>" + family[i].position + "</p>"
    +   "<p>" + family[i].name + "</p>"
    +   "<p>" + family[i].subjugation + "</p>";
}
Mike LaPan
Mike LaPan
5,190 Points
Mike LaPan
Mike LaPan
5,190 Points

I used this to access the individual titles. Is this right, or is there a better way?

    var keys = Object.keys(family[0]);
    console.log(keys[0]);
Mike LaPan
Mike LaPan
5,190 Points
Mike LaPan
Mike LaPan
5,190 Points

LOL, it was within John's "for in" loop above. Yeah, without it I doubt it would work. :-)

Steven Parker
Steven Parker
230,274 Points
Steven Parker
Steven Parker
230,274 Points

This struck me as funny...

for(i = 0; i < family.length; i += 1){
    html+= "<h3>" + family[i].title + "</h3>";
}
//I understand that family[i].title accesses the value
//how would I access the key?

But ... you're using the key to access the value! The key here is "title" :smile: