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JavaScript JavaScript Loops, Arrays and Objects Tracking Data Using Objects The Student Record Search Challenge Solution

Posted by john larson
john larson
16,594 Points

I looked in the MDN, stack overflow, and w3schools and I couldn't find how to sort an object within an array...

I would like to print the names alphabetically from these objects nested within an array. Here is the array/object

 var students = [

    {
        name: "Dionne",
        position: "Matriarch",
        title: "Derblin Prime",
        subjugation: "Supreme"
    },
    {
        name: "Soup Can",
        position: "Daughter1",
        title: "Derblin Squared",
        subjugation: "Lateral"
    },
    {
        name: "Sageling",
        position: "Daughter2",
        title: "Derblin Cubed",
        subjugation: "Lateral"
    },
    {
        name: "Soup Ladel",
        position: "Patriarch",
        title: "Derblin Extraneous",
        subjugation: "underling"
    }
];

here is the code to print the names

var i;
var names = "";
var message = "";

names += "<p>Student names: </p>";
for(i = 0; i < students.length; i += 1){
    names += "<li>" + students[i].name + "</li> ";
    print(names);
}

it prints the names fine but it would make sense for them to be in alphabetical order...if that's possible

5 Answers

Qasim Hafeez
Qasim Hafeez
12,731 Points
Qasim Hafeez
Qasim Hafeez
12,731 Points

john larson,

This is how I got it to work 

function compare(s1, s2){

  if(s1.name > s2.name){
    return 1;
  } else if (s1.name < s2.name){
    return -1;
  } else{
    return 0;
  }



}

students.sort(compare);

  var i;
var names = "";
var message = "";

names += "<p>Student names: </p>";
for(i = 0; i < students.length; i += 1){
    names += "<li>" + students[i].name + "</li> \n";

}

console.log(names);

I'm not clear on how exactly the compare function works in this case but, it lists the names alphabetically for me. Also, you say it printed out the names for you but when I ran your code the print window popped up. I used console.log to print the names to the console. You'll notice I put the 'console.log(names)' on the outside of the loop, otherwise it prints out four lists of names, with the only complete one being the last one.

john larson
john larson
16,594 Points

Thanks Quasim, That weird print thing that pops up sometimes, don't know what up with that. I thought it was some glitch on my pc but...it happened to you too. I got it to print to the page though, thanks. I would ask you to explain some of it to me but...sounds like it a bit of a mystery to you too. Peace my friend :D

srikarvedantam
srikarvedantam
8,369 Points
srikarvedantam
srikarvedantam
8,369 Points

You can use the "sort(...)" method available on arrays to sort its items. Further, you need to tell the sort(...) method how to "compare" two items. Here's how you can sort the "students" collection by student's name property:

function compare(s1, s2) {
    if (s1.name < s2.name)
        return -1;
    if (s1.name > s2.name)
        return 1;
    return 0;
}

students.sort(compare);

Just add the above code before you print the names, so that sorted student names will get printed out.

john larson
john larson
16,594 Points

Hi Srikar, sort() is the first thing I thought to try. I couldn't (and still can't) get it to work. Where would I pass the names, before the loop? after? then there's the issue that the names are actually in an object nested within an array. I don't see how to make this function work. Any additional insight would be greatly appreciated. Thank you

srikarvedantam
srikarvedantam
8,369 Points
srikarvedantam
srikarvedantam
8,369 Points

sort(...) is a built-in method; it is expected to run faster than a typical implementation. If it's speed is not satisfactory, a custom sort routine needs to be implemented and "Sorting" techniques, one of the oldest and long studied computing problem, warrants a different course altogether.

Erdem Meral
Erdem Meral
25,022 Points
Erdem Meral
Erdem Meral
25,022 Points

Also another problem is the speed. I dont think that the solution above is fast enough.

Hope Dave can help us :)