62 lines
1.1 KiB
JavaScript
62 lines
1.1 KiB
JavaScript
'use strict';
|
|
|
|
// there's 3 implementations written in increasing order of efficiency
|
|
|
|
// 1 - no Set type is defined
|
|
function uniqNoSet(arr) {
|
|
var ret = [];
|
|
|
|
for (var i = 0; i < arr.length; i++) {
|
|
if (ret.indexOf(arr[i]) === -1) {
|
|
ret.push(arr[i]);
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|
|
|
|
// 2 - a simple Set type is defined
|
|
function uniqSet(arr) {
|
|
var seen = new Set();
|
|
return arr.filter(function (el) {
|
|
if (!seen.has(el)) {
|
|
seen.add(el);
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
});
|
|
}
|
|
|
|
// 3 - a standard Set type is defined and it has a forEach method
|
|
function uniqSetWithForEach(arr) {
|
|
var ret = [];
|
|
|
|
(new Set(arr)).forEach(function (el) {
|
|
ret.push(el);
|
|
});
|
|
|
|
return ret;
|
|
}
|
|
|
|
// V8 currently has a broken implementation
|
|
// https://github.com/joyent/node/issues/8449
|
|
function doesForEachActuallyWork() {
|
|
var ret = false;
|
|
|
|
(new Set([true])).forEach(function (el) {
|
|
ret = el;
|
|
});
|
|
|
|
return ret === true;
|
|
}
|
|
|
|
if ('Set' in global) {
|
|
if (typeof Set.prototype.forEach === 'function' && doesForEachActuallyWork()) {
|
|
module.exports = uniqSetWithForEach;
|
|
} else {
|
|
module.exports = uniqSet;
|
|
}
|
|
} else {
|
|
module.exports = uniqNoSet;
|
|
}
|