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Today I had a need to sort and remove duplicate entries from an array in JavaScript. I figured I’d share the code for those interested. Here is the code for sorting. This uses a simple Bubble Sort.
Array.prototype.sort = function(comparator) {
var top = this.length;
var newTop = 0, index = 0, temp = 0;
do {
newTop = 0;
for (index = 1; index < top; index++) {
if ((comparator.call(this, this[index - 1], this[index])) > 0) {
temp = this[index];
this[index] = this[index - 1];
this[index - 1] = temp;
newTop = index;
}
}
top = newTop;
} while(top > 0);
};For the task of removing duplicates I am simply looping and splicing. I’m betting there is a more efficient way to do this, especially since I am sorting the array before removing duplicates, but this will have to do for now. I may do a follow up post with that in mind…
Array.prototype.dedupe = function(comparators) {
this.sort(comparators.sortComparator);
var index = 0, length = this.length, spliceIndex = 0, inner = 0;
var item = 0, compareResult = 0;
for (index = 0; index < length; index++) {
item = this[index];
if (index < length - 1 && length > index + 1) {
for (inner = index + 1; inner < length; inner++) {
compareResult = comparators.dedupeComparator.call(this, item, this[inner]);
if (compareResult === true) {
this.splice(index + 1, 1);
length--;
}
}
}
}
};And finally an example of their use. Run it, and give it a try. Happy coding!
var a = [
1, 4, 3, 0, 4, 5, 1, 0, 7, 7, 2, 3, 10
];
a.dedupe({
sortComparator: function(a, b) {
if (a > b)
return 1;
else if (a < b)
return -1;
else
return 0;
},
dedupeComparator: function(a, b) {
return a === b;
}
});
console.log("was [1, 4, 3, 0, 4, 5, 1, 0, 7, 7, 2, 3, 10], now %o", a);