Javascript array sorting problem

Question

I have an JavaScript arraylike this:

a[0][0] = "apple";
a[0][1] = 6.5;
a[1][0] = "orange";
a[1][1] = 4.3;
a[2][0] = "pear";
a[2][1] = 3.1;

I want to sort by the float number field in ascending order and assign the content in ascending order as well.

i.e.

a[0][0] = "pear";
a[1][1] = 3.1;
a[1][0] = "orange";
a[1][1] = 4.3;
a[2][0] = "apple";
a[2][1] = 6.5;

I have tried sorted the content but the code seems does not allow float number.

Also, I do not know how to reassign the content in ascending order. Can anyone help me?

 a.sort(function(a,b){return a[1] - b[1];});

try a.sort(function(a,b){return a[1] > b[1];}); ? negatives value returns true, I think — BiAiB
– BiAiB, Commented Feb 15, 2011 at 15:50
What error are you seeing? That code works, at least for the main sort: jsbin.com/ulite3 — T.J. Crowder
– T.J. Crowder, Commented Feb 15, 2011 at 15:50
@BiAiB: No, the function that sort calls is expected to return <0 if a should be before b, >0 if a should be after b, or 0 if they're the same. — T.J. Crowder
– T.J. Crowder, Commented Feb 15, 2011 at 15:51
@T.J. Crowder: Regarding your comment to my (incorrect) answer: The code shown above to set up the array would not work as it is. One would still have to do a[i] = [] and a = []. — Felix Kling
– Felix Kling, Commented Feb 15, 2011 at 15:55

T.J. Crowder · Accepted Answer · 2011-02-15 15:56:07Z

Provided the parts of your code that you haven't quoted are correct, that should work

var index;
var a = [];  // inferred

a[0] = [];   // inferred
a[1] = [];   // inferred
a[2] = [];   // inferred

a[0][0] = "apple";
a[0][1] = 6.5;
a[1][0] = "orange";
a[1][2] = 4.3;
a[2][0] = "pear";
a[2][3] = 3.1;

a.sort(function(a,b){
  return a[1] - b[1];
});

for (index = 0; index < a.length; ++index) {
  display(a[index].join());
}

Live copy

Output:

pear,3.1
orange,4.3
apple,6.5

Off-topic: A more efficient, and perhaps clearer, way to initialize that array:

var a = [
    ["apple", 6.5],
    ["orange", 4.3],
    ["pear", 3.1]
];

Live copy

kennebec · Accepted Answer · 2011-02-15 15:55:55Z

2

Did you create the array correctly? Your sort function is correct...

var a=[['apple',6.5],['orange',4.3],['pear',3.1]];
a.sort(function(a,b){return a[1]-b[1]});

/*  returned value: (Array)
pear,3.1,orange,4.3,apple,6.5
*/

answered Feb 15, 2011 at 15:55

kennebec

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Comments

Siedrix · Accepted Answer · 2011-02-15 15:50:57Z

0

You just need to change the a, b order in the sort function

a.sort(function(a,b){return b[1] -a[1];});

try this in your firebug, , dragonfly or webkit console

var a = [["apple",6.5],["orange",4.3],["pear",3.1]];
a.sort(function(a,b){return b[1] -a[1];});

console.log(a);

answered Feb 15, 2011 at 15:50

Siedrix

6414 silver badges10 bronze badges

1 Comment

T.J. Crowder Over a year ago

His code works fine; yours gives the array backward. See jsbin.com/ulite3 (his version).

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