在javascript中按子数组值对数组排序

Question

I have an array of arrays in javascript with a distance (integer, whole number) value. I am trying to sort them, but I can't seem to get this to work.

nodes = [[{distance:15}],[{distance:123}],[{distance:2}]];

function sortNodes(a,b) {
   if (a.distance < b.distance)
     return -1;
   if (a.distance > b.distance)
     return 1;
     return 0;
   }
console.log(nodes.slice(0).sort(sortNodes));

Need some direction on what is happening here and why.

Answer 1

You need to do return a[0].distance - b[0].distance; this is because:

1. distance is a integer type so you do not need to compare that and return 1 , -1 or 0 using comparison operator.
2. You have array of arrays with one object inside the nested array so use [0] to get that object inside parameter a and b .

 var nodes = [ [{ distance: 15 }], [{ distance: 123 }], [{ distance: 2 }] ]; function sortNodes(a, b) { return a[0].distance - b[0].distance; } console.log(nodes.slice(0).sort(sortNodes)); 

Answer 2

The comparator function that is passed to the sort() function takes the values from the array.

So, as you have mentioned that you have an array of arrays , the arguments of the comparator function would be arrays.

Thus, you can use a[0] and b[0] to access the objects.

Here is the code:

nodes = [[{ distance: 15 }], [{ distance: 123 }], [{ distance: 2 }]];

function sortNodes(a, b) {
    if (a[0].distance < b[0].distance) return -1;
    if (a[0].distance > b[0].distance) return 1;
    return 0;
}
console.log(nodes.slice(0).sort(sortNodes));

Here is nice de-structuring example:

nodes = [[{ distance: 15 }], [{ distance: 123 }], [{ distance: 2 }]];

function sortNodes([a], [b]) {
    return a.distance - b.distance
}
console.log(nodes.slice(0).sort(sortNodes));

Answer 3

This will also work:

nodes = [[{distance:15}],[{distance:123}],[{distance:2}]];

function sortNodes(a,b) {
    return a[0].distance > b[0].distance;
}
console.log(nodes.slice(0).sort(sortNodes));