Given an array of objects like this:
objects = [
{ id: 'aaaa', description: 'foo' },
{ id: 'bbbb', description: 'bar' },
{ id: 'cccc', description: 'baz' }
];
And an array of strings like this:
order = [ 'bbbb', 'aaaa', 'cccc' ];
How would I sort the first array so that the id attribute matches the order of the second array?
Try this:
objects.sort(function(a, b){
return order.indexOf(a.id) - order.indexOf(b.id)
});
Assuming the variables are like you declared them in the question, this should return:
[
{ id: 'bbbb', description: 'bar' },
{ id: 'aaaa', description: 'foo' },
{ id: 'cccc', description: 'baz' }
];
(It actually modifies the objects variable)
objects that aren't in the orders array they appear at the top. Is there a way to make those show up at the end of the list instead of the start?
indexOf values for -1, and if they are -1 return Number.MAX_VALUE instead.You need a way to translate the string into the position in the array, i.e. an index-of function for an array.
There is one in newer browsers, but to be backwards compatible you need to add it if it's not there:
if (!Array.prototype.indexOf) {
Array.prototype.indexOf = function(str) {
var i;
for (i = 0; i < this.length; i++) if (this[i] == str) return i;
return -1;
}
}
Now you can sort the array by turning the string into an index:
objects.sort(function(x,y){ return order.indexOf(x.id) - order.indexOf(y.id); });
/* Create a mapping object `orderIndex`:
{
"bbbb": 0,
"aaaa": 1,
"cccc": 2
}
*/
const orderIndex = {}
order.forEach((value, index) => orderIndex[value] = index);
// Sort
objects.sort((a, b) => orderIndex[a.id] - orderIndex[b.id]);
// data
const objects = [
{ id: 'aaaa', description: 'foo' },
{ id: 'bbbb', description: 'bar' },
{ id: 'cccc', description: 'baz' }
];
const order = [ 'bbbb', 'aaaa', 'cccc' ];
/* Create a mapping object `orderIndex`:
{
"bbbb": 0,
"aaaa": 1,
"cccc": 2
}
*/
const orderIndex = {}
order.forEach((value, index) => orderIndex[value] = index);
// Sort
objects.sort((a, b) => orderIndex[a.id] - orderIndex[b.id]);
// Log
console.log('orderIndex:', orderIndex);
console.log('objects:', objects);