Unknown Javascript error

Question

I am trying to sort an array into descending order.

This is my current code:

for(var i = 0; i < scoresArray.length; i){
function swap(a, b) {
            var temp = scoresArray[a].score;
            scoresArray[a] = scoresArray[b].score;
            scoresArray[b] = temp;
}
    for(var x = 0; x < scoresArray.length; x++){
        if(scoresArray[x].score < scoresArray[++x].score){
            console.log(x);
            swap(x, ++x);
        }
    }
}
return scoresArray.content;

This is the input array:

  [
    { url: 'www.lboro.ac.uk', score: 6 },
    { url: 'www.xyz.ac.uk', score: 3 },
    { url: 'www', score: 8 } ]

This (should be) the output array:

  [{ url: 'www.xyz.ac.uk', score: 3 },
    { url: 'www.lboro.ac.uk', score: 6 },
    { url: 'www', score: 8 } ]

What do you want it to be sorted for? score or Url? u mentioned descending order... the score seems to be in ascending order in ur output? — ajc
– ajc, Commented Nov 9, 2013 at 23:43

Oriol · Accepted Answer · 2013-11-10 00:33:13Z

2

Like @Douglas said, using array.sort(compareFunction) makes this easier:

var scoresArray = [
    { url: 'www.lboro.ac.uk', score: 6 },
    { url: 'www.xyz.ac.uk', score: 3 },
    { url: 'www', score: 8 } ];
scoresArray.sort(function(a,b) {
    return a.score - b.score;
});

Note that, since scoresArray[i].score are numbers, you can use return a.score - b.score. In a more general case (e.g. if they were strings), you could use

scoresArray.sort(function(a,b) {
    if(a.score > b.score) return 1;
    if(a.score < b.score) return -1;
    return 0;
});

edited Nov 10, 2013 at 0:33

answered Nov 9, 2013 at 23:42

Oriol

291k71 gold badges459 silver badges535 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

jfriend00 Over a year ago

Your .sort function can just be return b.score - a.score; to get a reverse sort. You don't need any if statements.

Douglas · Accepted Answer · 2013-11-10 00:07:35Z

1

The swap function isn't working, it replaces the values in scoresArray with just the score numbers. It is also important to know that ++x changes the value of x. I think you mean x + 1 instead.

This roughly works:

var scoresArray = [
    { url: 'www.lboro.ac.uk', score: 6 },
    { url: 'www.xyz.ac.uk', score: 3 },
    { url: 'www', score: 8 } ];

function swap(a, b) {
    var temp = scoresArray[a];
    scoresArray[a] = scoresArray[b];
    scoresArray[b] = temp;
}

for(var i = 0; i < scoresArray.length; i++) {
    for(var x = 0; x < scoresArray.length - 1; x++) {
        if (scoresArray[x].score > scoresArray[x + 1].score) {
            swap(x, x + 1);
        }
    }
}

console.log(scoresArray);

But it would be better to use array.sort:

var scoresArray = [
    { url: 'www.lboro.ac.uk', score: 6 },
    { url: 'www.xyz.ac.uk', score: 3 },
    { url: 'www', score: 8 } ];

scoresArray.sort(function(a, b) {
    return b.score - a.score;
});

console.log(scoresArray);

edited Nov 10, 2013 at 0:07

answered Nov 9, 2013 at 23:44

Douglas

37.8k9 gold badges80 silver badges91 bronze badges

1 Comment

jfriend00 Over a year ago

Your .sort function can just be return b.score - a.score; to get a reverse sort. You don't need any if statements.

Collectives™ on Stack Overflow

Unknown Javascript error

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related