First, in JavaScript it's generally not a good idea to iterate over arrays using for ... in
. See Why is using "for...in" with array iteration a bad idea? for details.
So you might try something like this:
var groups = {};
for (var i = 0; i < myArray.length; i++) {
var groupName = myArray[i].group;
if (!groups[groupName]) {
groups[groupName] = [];
}
groups[groupName].push(myArray[i].color);
}
myArray = [];
for (var groupName in groups) {
myArray.push({group: groupName, color: groups[groupName]});
}
Using the intermediary groups
object here helps speed things up because it allows you to avoid nesting loops to search through the arrays. Also, because groups
is an object (rather than an array) iterating over it using for ... in
is appropriate.
Addendum
FWIW, if you want to avoid duplicate color entries in the resulting arrays you could add an if
statement above the line groups[groupName].push(myArray[i].color);
to guard against duplicates. Using jQuery it would look like this;
if (!$.inArray(myArray[i].color, groups[groupName])) {
groups[groupName].push(myArray[i].color);
}
Without jQuery you may want to add a function that does the same thing as jQuery's inArray
:
Array.prototype.contains = function(value) {
for (var i = 0; i < this.length; i++) {
if (this[i] === value)
return true;
}
return false;
}
and then use it like this:
if (!groups[groupName].contains(myArray[i].color)) {
groups[groupName].push(myArray[i].color);
}
Note that in either case you are going to slow things down a bit due to all the extra iteration, so if you don't need to avoid duplicate color entries in the result arrays I would recommend avoiding this extra code. There
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Created by neuronaut on 2020-03-10 03:05:45 +0000 UTC
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