Last change
on this file since fa375fe was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago |
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[6a3a178] | 1 | 'use strict';
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| 2 |
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| 3 | // there's 3 implementations written in increasing order of efficiency
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| 4 |
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| 5 | // 1 - no Set type is defined
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| 6 | function uniqNoSet(arr) {
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| 7 | var ret = [];
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| 8 |
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| 9 | for (var i = 0; i < arr.length; i++) {
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| 10 | if (ret.indexOf(arr[i]) === -1) {
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| 11 | ret.push(arr[i]);
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| 12 | }
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| 13 | }
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| 14 |
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| 15 | return ret;
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| 16 | }
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| 17 |
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| 18 | // 2 - a simple Set type is defined
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| 19 | function uniqSet(arr) {
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| 20 | var seen = new Set();
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| 21 | return arr.filter(function (el) {
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| 22 | if (!seen.has(el)) {
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| 23 | seen.add(el);
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| 24 | return true;
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| 25 | }
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| 26 |
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| 27 | return false;
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| 28 | });
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| 29 | }
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| 30 |
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| 31 | // 3 - a standard Set type is defined and it has a forEach method
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| 32 | function uniqSetWithForEach(arr) {
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| 33 | var ret = [];
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| 34 |
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| 35 | (new Set(arr)).forEach(function (el) {
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| 36 | ret.push(el);
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| 37 | });
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| 38 |
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| 39 | return ret;
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| 40 | }
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| 41 |
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| 42 | // V8 currently has a broken implementation
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| 43 | // https://github.com/joyent/node/issues/8449
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| 44 | function doesForEachActuallyWork() {
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| 45 | var ret = false;
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| 46 |
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| 47 | (new Set([true])).forEach(function (el) {
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| 48 | ret = el;
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| 49 | });
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| 50 |
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| 51 | return ret === true;
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| 52 | }
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| 53 |
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| 54 | if ('Set' in global) {
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| 55 | if (typeof Set.prototype.forEach === 'function' && doesForEachActuallyWork()) {
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| 56 | module.exports = uniqSetWithForEach;
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| 57 | } else {
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| 58 | module.exports = uniqSet;
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| 59 | }
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| 60 | } else {
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| 61 | module.exports = uniqNoSet;
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| 62 | }
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